- Complete working configuration for FM350-GL modem - CYTA Cyprus APN setup (internet) - AT command reference and troubleshooting guide - Configuration scripts and documentation - RNDIS mode working with manual IP configuration
213 lines
4.5 KiB
Markdown
213 lines
4.5 KiB
Markdown
# Alpine 5G Router - Raspberry Pi 5 + Fibocom FM350-GL
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A complete 5G router setup using Alpine Linux on Raspberry Pi 5 with a Fibocom FM350-GL modem.
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## ✅ Status: Working
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The 5G modem is fully operational with CYTA Cyprus SIM card.
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## Documentation
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| File | Description |
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|------|-------------|
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| [README.md](README.md) | This file - overview and quick start |
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| [5G_MODEM_TROUBLESHOOTING.md](5G_MODEM_TROUBLESHOOTING.md) | Complete modem configuration reference |
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| [configure_fm350_5g.sh](configure_fm350_5g.sh) | Configuration script for the modem |
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## Hardware
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- **Board:** Raspberry Pi 5
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- **Modem:** Fibocom FM350-GL (USB ID: 0e8d:7126)
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- **OS:** Alpine Linux v3.23.3
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- **SIM:** CYTA Cyprus (APN: `internet`)
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## Network Architecture
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```
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Internet (CYTA 5G)
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│
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▼
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FM350-GL Modem
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(RNDIS eth1)
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│
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▼
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Raspberry Pi 5
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Alpine Linux
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│
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▼
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eth0.100 VLAN
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(192.168.1.1)
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│
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▼
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LAN Clients
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```
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## Quick Start
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### 1. Install Required Packages
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```bash
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# Enable community repository
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sed -i 's|#.*community|http://mirrors.neterra.net/alpine/v3.23/community|' /etc/apk/repositories
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apk update
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# Install packages
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apk add modemmanager dnsmasq iptables libmbim-tools qmi-utils
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```
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### 2. Configure and Connect Modem
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```bash
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# Set APN for CYTA
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cat /dev/ttyUSB1 & CAT_PID=$!
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sleep 0.3
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echo -e 'AT+CGDCONT=1,"IP","internet"\r' > /dev/ttyUSB1
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sleep 2
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kill $CAT_PID
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# Activate connection
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cat /dev/ttyUSB1 & CAT_PID=$!
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sleep 0.3
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echo -e 'AT+CGACT=1,1\r' > /dev/ttyUSB1
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sleep 3
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kill $CAT_PID
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# Get modem IP
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cat /dev/ttyUSB1 & CAT_PID=$!
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sleep 0.3
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echo -e 'AT+CGPADDR=1\r' > /dev/ttyUSB1
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sleep 2
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kill $CAT_PID
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# Note the IP address returned (e.g., 10.156.167.104)
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```
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### 3. Configure Network Interface
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```bash
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# Replace MODEM_IP with the IP from AT+CGPADDR=1
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MODEM_IP="10.156.167.104"
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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 connectivity
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ping -c 3 8.8.8.8
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```
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### 4. Setup NAT for LAN
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```bash
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# Enable IP forwarding
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echo 1 > /proc/sys/net/ipv4/ip_forward
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# Configure NAT
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iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE
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iptables -A FORWARD -i eth0.100 -o eth1 -j ACCEPT
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iptables -A FORWARD -i eth1 -o eth0.100 -m state --state RELATED,ESTABLISHED -j ACCEPT
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# Save rules
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iptables-save > /etc/iptables/rules.v4
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```
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## Key Configuration Details
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### Modem USB Modes
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| Mode | USB ID | Description | Status |
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|------|--------|-------------|--------|
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| 40 | 0e8d:7126 | RNDIS mode | ✅ Working |
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| 41 | 0e8d:7127 | Extended mode | ❌ AT broken |
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**Important:** Stay in Mode 40 - AT commands work on `/dev/ttyUSB1`.
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### Working AT Commands
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| Command | Description |
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|---------|-------------|
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| `AT` | Test communication |
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| `AT+CSQ` | Signal strength |
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| `AT+CGDCONT=1,"IP","internet"` | Set APN |
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| `AT+CGACT=1,1` | Activate connection |
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| `AT+CGPADDR=1` | Get assigned IP |
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| `AT+CGCONTRDP=1` | Get DNS servers |
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| `AT+GTUSBMODE?` | Check USB mode |
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### CYTA Cyprus Network Info
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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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## Services
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The following services are configured to start on boot:
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```bash
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# Check service status
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rc-status
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# Services enabled:
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# - dnsmasq (DHCP/DNS)
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# - iptables-restore (firewall rules)
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# - 5g-router (connection script)
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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` | Startup connection script |
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| `/etc/init.d/5g-router` | OpenRC service |
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| `/etc/init.d/iptables-restore` | Firewall restore service |
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| `/etc/iptables/rules.v4` | Saved firewall rules |
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| `/etc/dnsmasq.conf` | DHCP configuration |
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| `/etc/network/interfaces` | Network configuration |
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| `/var/log/5g-router.log` | Connection log |
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## Troubleshooting
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### Modem not responding to AT commands
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1. Check modem is in Mode 40: `lsusb | grep 7126`
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2. Use `/dev/ttyUSB1` for AT commands
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3. Don't use `stty` - send commands directly
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### DHCP not working on eth1
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This is normal - RNDIS mode doesn't provide DHCP. Configure IP manually using the address from `AT+CGPADDR=1`.
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### Connection drops
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Re-run the connection script:
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```bash
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/usr/local/bin/connect-5g.sh
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```
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Or restart the service:
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```bash
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service 5g-router restart
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```
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## Verification Commands
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```bash
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# Check modem
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lsusb | grep -i fibocom
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# Check network
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ip addr show eth1
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ip route show
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# Test connectivity
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ping -c 3 8.8.8.8
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ping -c 3 google.com
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# Check NAT rules
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iptables -t nat -L -n -v
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# View logs
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tail -f /var/log/5g-router.log
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```
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