9dc35a57a2
- Introduced a web GUI for managing 5G connections, replacing the standalone 5g-router service. - Updated scripts to ensure exclusive access to the AT port, preventing conflicts. - Improved troubleshooting documentation in 5G_MODEM_TROUBLESHOOTING.md, adding checks for processes using the AT port. - Enhanced connection management in the web app, including auto-connect and detailed status APIs. - Updated installation scripts to reflect changes in service management and dependencies.
331 lines
11 KiB
Markdown
331 lines
11 KiB
Markdown
# Fibocom FM350-GL 5G Modem Configuration Guide
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Complete reference for configuring the Fibocom FM350-GL modem on Alpine Linux.
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## Working Configuration
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| Setting | Value |
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|---------|-------|
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| **Modem** | Fibocom FM350-GL |
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| **USB ID** | 0e8d:7126 (Mode 40) |
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| **AT Port** | /dev/ttyUSB1 |
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| **Network Interface** | eth1 (RNDIS) |
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| **APN** | internet (CYTA Cyprus) |
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## AT Command Reference
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### Sending AT Commands
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The FM350-GL doesn't need `stty` configuration. Send commands directly:
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```bash
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# Pattern for sending AT commands
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cat /dev/ttyUSB1 & CAT_PID=$!
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sleep 0.3
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echo -e 'YOUR_COMMAND\r' > /dev/ttyUSB1
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sleep 2
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kill $CAT_PID 2>/dev/null
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```
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### Essential Commands
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| Command | Purpose | Example Response |
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|---------|---------|------------------|
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| `AT` | Test communication | `OK` |
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| `AT+CGMI` | Manufacturer | `Fibocom Wireless Inc.` |
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| `AT+CGMM` | Model | `FM350-GL` |
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| `AT+CSQ` | Signal strength | `+CSQ: 7, 99` (7 = moderate) |
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| `AT+CREG?` | Network registration | `+CREG: 0,1` (1 = registered) |
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| `AT+CEREG?` | LTE/5G registration | `+CEREG: 0,1` |
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| `AT+CCID` | SIM card ID | `+CCID: 893570...` |
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### APN Configuration
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```bash
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# Set APN (CYTA Cyprus uses "internet")
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echo -e 'AT+CGDCONT=1,"IP","internet"\r' > /dev/ttyUSB1
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# Verify APN is set
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echo -e 'AT+CGDCONT?\r' > /dev/ttyUSB1
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# Response: +CGDCONT: 1,"IP","internet",""...
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```
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### Connection Management
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```bash
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# Activate PDP context (start data connection)
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echo -e 'AT+CGACT=1,1\r' > /dev/ttyUSB1
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# Response: +CGEV: ME PDN ACT 1, OK
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# Get assigned IP address
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echo -e 'AT+CGPADDR=1\r' > /dev/ttyUSB1
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# Response: +CGPADDR: 1,"10.156.167.104",""
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# Get full connection details (DNS, MTU)
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echo -e 'AT+CGCONTRDP=1\r' > /dev/ttyUSB1
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# Response includes DNS servers
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```
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### USB Mode Control
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```bash
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# Check current USB mode
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echo -e 'AT+GTUSBMODE?\r' > /dev/ttyUSB1
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# Response: +GTUSBMODE: 40
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# Available modes
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echo -e 'AT+GTUSBMODE=?\r' > /dev/ttyUSB1
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# Response: +GTUSBMODE: (40,41)
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# Switch modes (requires modem reset)
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echo -e 'AT+GTUSBMODE=40\r' > /dev/ttyUSB1
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# Reset modem
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echo -e 'AT+CFUN=1,1\r' > /dev/ttyUSB1
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```
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## USB Modes
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| Mode | USB Product ID | Description | AT Commands |
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|------|----------------|-------------|-------------|
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| 40 | 0e8d:7126 | RNDIS mode | ✅ Work on ttyUSB1 |
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| 41 | 0e8d:7127 | Extended mode | ❌ Don't work |
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**Important:** Stay in Mode 40 for reliable AT command access.
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## Network Interface Configuration
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### Why DHCP Doesn't Work
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The RNDIS interface (`eth1`) does **not** provide DHCP. The modem does not assign an IP to the host via DHCP. You must:
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1. Get the IP from the modem via **`AT+CGPADDR=1`**
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2. Optionally get DNS via **`AT+CGCONTRDP=1`** (connection dynamic parameters)
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3. Configure the interface and `/etc/resolv.conf` manually
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The **connect-5g.sh** script does exactly this: it uses AT commands only (no DHCP on eth1), then sets `ip addr` and default route on eth1, and DNS from modem or from config.
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### Manual Configuration
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```bash
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# Get IP from modem (replace with actual value)
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MODEM_IP="10.156.167.104"
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# Configure interface
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ip link set eth1 up
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ip addr flush dev eth1
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ip addr add $MODEM_IP/32 dev eth1
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ip route add default dev eth1 metric 50
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# Test
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ping -c 3 8.8.8.8
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```
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## CYTA Cyprus Settings
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| Setting | Value |
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|---------|-------|
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| APN | `internet` |
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| DNS Primary | 195.14.130.220 |
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| DNS Secondary | 195.14.154.100 |
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| Network Name | Vodafone |
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## Complete Connection Sequence
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```bash
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#!/bin/sh
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# Full connection sequence for FM350-GL with CYTA SIM
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AT_PORT="/dev/ttyUSB1"
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APN="internet"
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# 1. Configure APN
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cat $AT_PORT & PID=$!; sleep 0.3
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echo -e "AT+CGDCONT=1,\"IP\",\"$APN\"\r" > $AT_PORT
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sleep 2; kill $PID 2>/dev/null
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# 2. Activate connection
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cat $AT_PORT & PID=$!; sleep 0.3
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echo -e "AT+CGACT=1,1\r" > $AT_PORT
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sleep 3; kill $PID 2>/dev/null
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# 3. Get IP address
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MODEM_IP=$(timeout 5 sh -c "
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cat $AT_PORT & PID=\$!
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sleep 0.3
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echo -e 'AT+CGPADDR=1\r' > $AT_PORT
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sleep 2
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kill \$PID 2>/dev/null
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" 2>&1 | grep CGPADDR | grep -oE '[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+' | head -1)
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echo "Modem IP: $MODEM_IP"
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# 4. Configure interface
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ip link set eth1 up
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ip addr flush dev eth1
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ip addr add $MODEM_IP/32 dev eth1
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ip route add default dev eth1 metric 50
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# 5. Test
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ping -c 3 8.8.8.8
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```
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## Troubleshooting
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### Run full diagnostic (modem not responding after reboot)
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**When the modem does not respond** after a reboot, run the full troubleshoot script on the device to collect all logs and checks:
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```bash
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# On the device (SSH or console)
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/usr/local/bin/troubleshoot-5g.sh
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```
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If the script is not installed yet, deploy first (`./scripts/deploy.sh` or `./scripts/install.sh` on the device), or run from the repo:
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```bash
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./scripts/troubleshoot-5g.sh
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```
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The script prints:
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- **dmesg** (last 40 lines) – kernel messages about USB/tty
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- **lsusb** – modem present and Mode 40 (7126) vs Mode 41 (7127)
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- **/dev/ttyUSB*** – whether each port is a character device or a broken regular file
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- **AT test** on the configured port (with 3s wait, like connect-5g.sh)
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- **AT probe** on each ttyUSB port – which port returns OK
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- **5g-router service** status
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- **WAN interface** and default route
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- **Last 60 lines** of `/var/log/5g-router.log`
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- **Processes using the AT port** (lsof) – see if ModemManager or another process is holding the port
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- **modem-status-at.sh** output (registration, signal) if installed
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Copy the full output and use it to see: wrong AT port, broken ttyUSB node, modem in Mode 41, another process holding the port, or service/APN issues. Then apply the fixes listed at the end of the script or in the sections below.
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### AT Commands Not Responding / "AT not OK"
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**Symptoms:** No response to AT commands, or connect script logs "AT not OK".
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**Solutions:**
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1. **Wait longer** – The modem can take 2–4 seconds to respond. The script now waits 3 s for the initial AT. If you still see "AT not OK", increase the wait in `get_at_response` or in config.
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2. Check modem is in Mode 40: `lsusb | grep 7126`
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3. If in Mode 41 (7127), AT commands won't work - need physical access to switch back
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4. **Try different ports** – On FM350-GL the AT port is often ttyUSB1, but it can be ttyUSB0 or another. Test manually:
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```bash
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( timeout 5 cat /dev/ttyUSB1 & ); sleep 0.5; echo -e 'AT\r' > /dev/ttyUSB1; sleep 3; kill %1 2>/dev/null
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```
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If you see `OK` in the output, that port works. Set `AT_PORT="/dev/ttyUSB1"` (or the working port) in `/etc/5g-router.conf`.
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5. **Ensure no other process is holding the port** (e.g. ModemManager, a stuck `cat`, or the Web GUI polling modem-status-at.sh). Run `lsof /dev/ttyUSB1` to see who has it open. Stop ModemManager if present: `rc-service ModemManager stop`. If the 5g-router service is stuck with an open `cat`, restart it: `service 5g-router restart`.
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### ttyUSB port shows as regular file (AT not responding)
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**Symptoms:** `ls -la /dev/ttyUSB1` shows `-rw-rw----` (regular file) instead of `crw-rw----` (character device). AT commands get no reply or garbage.
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**Cause:** A **shell redirect** to `/dev/ttyUSB1` when the device **does not exist yet** (e.g. modem not bound, or device removed) **creates a regular file** at that path. That file then “steals” the name: when the kernel later creates the real modem port, it may get a different name (e.g. ttyUSB5). Typical causes:
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- A script or cron job (e.g. Web GUI status poll, modem-status-at.sh) runs **before** the modem is ready and does `echo ... > /dev/ttyUSB1`.
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- The 5g-router service runs at boot; between “port available” and sending AT, the modem briefly disappears (USB glitch) and the next write creates a file.
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- ModemManager or another daemon opening the port when it doesn’t exist.
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**Prevention:** All project scripts that write to the AT port now check `[ -c "$AT_PORT" ]` immediately before writing and skip/exit if it’s not a character device, so they never create a regular file. The connection script also removes a stray `/dev/ttyUSB` (no number) file at startup.
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**Fix (one-time):**
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```bash
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# Replace N with the port number (0, 1, 2, …)
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rm -f /dev/ttyUSB1
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mknod /dev/ttyUSB1 c 188 1
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chmod 660 /dev/ttyUSB1
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chown root:dialout /dev/ttyUSB1
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```
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**Prevention:** `connect-5g.sh` now checks and fixes a broken AT port automatically before use (recreates the device node if it is a regular file). Scripts never write to the port unless it is currently a character device, so they don’t create the file in the first place.
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### Stray /dev/ttyUSB file (no number)
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**Symptoms:** Troubleshoot shows `/dev/ttyUSB` as a regular file (no digit). Real ports are ttyUSB0, ttyUSB1, etc.
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**Fix:** Remove the stray file. The connection script now removes it automatically; you can also run: `rm -f /dev/ttyUSB`
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### ttyUSB3 Shows as Regular File (legacy)
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**Symptoms:** `ls -la /dev/ttyUSB3` shows `-rw-r--r--` instead of `crw-rw----`
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**Fix:**
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```bash
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rm -f /dev/ttyUSB3
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mknod /dev/ttyUSB3 c 188 3
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chmod 660 /dev/ttyUSB3
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chown root:dialout /dev/ttyUSB3
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```
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### stty Errors
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**Symptoms:** `stty: /dev/ttyUSB1: cannot perform all requested operations`
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**Solution:** Don't use `stty`. Send AT commands directly with `echo` and `cat`.
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### No IP on eth1 / Could not get modem IP
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**Symptoms:** `ip addr show eth1` shows no inet address; or connect script logs "Could not get modem IP".
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**Solutions:**
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1. RNDIS doesn't use DHCP. The script gets the IP from `AT+CGPADDR=1`; if the operator hasn't assigned one yet, it retries a few times. Wait and re-run the connection script.
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2. Check registration and signal: run `AT+CEREG?` (expect `,1` or `,5` for registered) and `AT+CSQ` (signal strength). If not registered or no signal, fix antenna/SIM/location.
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3. Ensure APN is correct for your operator (e.g. `internet` for CYTA).
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4. Try activating PDP again: `AT+CGACT=1,1` then wait 5–10 s and `AT+CGPADDR=1`.
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### ModemManager Not Detecting Modem
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**Note:** ModemManager doesn't work well with this modem in RNDIS mode. Use AT commands directly instead.
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### Signal Strength Interpretation
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| CSQ Value | dBm | Quality |
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|-----------|-----|---------|
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| 0 | -113 or less | No signal |
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| 1-9 | -111 to -95 | Poor |
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| 10-14 | -93 to -85 | Fair |
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| 15-19 | -83 to -75 | Good |
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| 20-30 | -73 to -53 | Excellent |
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| 31 | -51 or better | Excellent |
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| 99 | Unknown | - |
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## Kernel Modules
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These modules should be loaded for MBIM/QMI support (optional):
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```bash
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modprobe cdc-wdm
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modprobe cdc_mbim
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modprobe qmi_wwan
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modprobe cdc_ncm
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# Verify
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lsmod | grep -E '(cdc|qmi)'
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```
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## Files on Device
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| Path | Purpose |
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|------|---------|
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| `/usr/local/bin/connect-5g.sh` | Auto-connection script |
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| `/usr/local/bin/troubleshoot-5g.sh` | Full diagnostic (logs + AT/USB checks) |
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| `/etc/init.d/5g-router` | OpenRC service |
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| `/var/log/5g-router.log` | Connection log |
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| `/etc/iptables/rules.v4` | Firewall/NAT rules |
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## Service Management
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```bash
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# Check status
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service 5g-router status
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# Restart connection
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service 5g-router restart
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# View logs
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tail -f /var/log/5g-router.log
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# Check if enabled at boot
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rc-update show | grep 5g-router
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```
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