LTE modem setup (SIM7600E-H-PCIE) for internet access

note

In the default firmware, ModemManager doesn't start automatically and may not function correctly. NetworkManager and mmcli are used for configuration, and routing is configured via netplan with explicit metrics.

1. Activating the SIM card and checking the modem

# Make sure the modem is displayed as a USB device (idVendor/idProduct)
lsusb | grep -i simtech

# Verify that ttyUSB* devices appear in the system after connecting the modem
dmesg | grep ttyUSB

# Verify that AT commands are working (on ttyUSB2 or ttyUSB3)
cu -l /dev/ttyUSB2 -s 115200

at
OK

ttyUSB port assignments

Port	Assignment
ttyUSB0	(qcdm) – QCDM protocol
ttyUSB1	(gps) – GNSS data (not implemented)
ttyUSB2	(at) – AT commands
ttyUSB3	(at) – AT commands
ttyUSB4	(audio) – PCM audio stream (not implemented)

To manage and configure the connection, use ttyUSB2 or ttyUSB3.

---

2. Configuring the connection via NetworkManager (working method)

# Create a GSM connection with the desired APN (example for Tele2)
mmcli -m 0 --enable

nmcli connection add type gsm ifname "*" con-name "Tele2" apn internet.tele2.ru
nmcli connection modify "Tele2" gsm.username "tele2" gsm.password "tele2"
nmcli connection modify "Tele2" connection.autoconnect yes

# Activate the connection
nmcli connection up "Tele2"
``

After this, an interface of type `ppp0` or `wwan0` should appear.

Connection check:

```bash
ip addr show ppp0

---

3. Configuring route metrics via netplan

Edit the file /etc/netplan/01-netcfg.yaml:

network:
version: 2
renderer: networkd
ethernets:
eth1:
dhcp4: false
dhcp6: false
addresses:
- 192.168.5.2/24
routes:
- to: 0.0.0.0/0
via: 192.168.5.100
metric: 1000
optional: yes

For LTE, the metric is usually set automatically (e.g., 700). For LTE to become the default gateway, the Ethernet metric must be higher.

If necessary, set the metric manually:

nmcli connection modify lte ipv4.route-metric 500

Apply the changes:

netplan apply

Check routing:

ip route show

Expected:

• ppp0 with a lower metric (~700 or lower)
• eth1 with a metric of 1000 or higher

4. Ensuring ModemManager autostart

systemctl enable ModemManager
systemctl start ModemManager

If necessary, add startup via /etc/rc.local or a systemd unit.

5. Alternative method via mmcli (without NetworkManager)

mmcli -m 0 -v --simple-connect="apn=internet.rtk.ru"

Check the connection status:

mmcli -m 0 --status
ip route

Warning

Do not use pppd with the SIM7600E-H-PCIE modem. When operating in PPP mode, the ttyUSB interfaces may be blocked, after which the modem becomes unavailable until a reboot.

6. Enabling autostart (optional)

systemctl enable ModemManager

If autostart doesn't work, use /etc/rc.local or a systemd unit.

info

If you don't have an internet connection after setup, check your signal strength with the command mmcli -m 0 --signal-get. Make sure your SIM card is activated (insert it into a regular phone and make a call).