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150Mbps 4G LTE USB Modem Setup

Not the recommended modem. Aircast auto-configures the SIM7600G-H HAT — plug it in and it just works. This generic USB stick isn't auto-detected, so it needs the manual setup below. Only reach for this guide if it's the modem you already have on hand.

This is one of those cheap, unbranded 4G sticks — about $8 on AliExpress. Out of the box it behaves like its own little WiFi router, but on a drone you want it feeding the Raspberry Pi directly over USB instead. The steps below flip it into USB network mode and get the Pi online. Set aside about 20 minutes, and be comfortable running a few commands over SSH.

Where to buy it on AliExpress

150Mbps 4G LTE USB Modem

Before you start

A few things to have ready:

  • The USB modem — the 150Mbps 4G LTE stick from the link above.
  • A SIM card with an active data plan, and no PIN lock.
  • Your Raspberry Pi with SSH access already working.
  • An internet connection on the Pi for now, so it can install a couple of packages.

Step-by-step setup

The whole point of these steps is to convert the modem from its default WiFi-hotspot mode into a plain USB network adapter. That gives the Pi a direct connection with lower latency and one less thing to go wrong.

1

Insert the SIM and plug it in

  1. Slide the back cover downward to open it.
  2. Insert the SIM card with the gold contacts facing down.
  3. Replace the cover and plug the modem into a USB port on the Pi.
  4. Give it about 30 seconds for the LED to come on.

Once the LED is on — solid or blinking — the modem has power.

Most carriers use internet as their APN, and this modem usually picks that up on its own. If you can't get online later, you may need to set the APN by hand through the modem's web interface at 192.168.1.1.

2

Install the mode-switch tools

SSH into the Pi and install usb-modeswitch — that's the tool that flips the modem out of WiFi mode.

sudo apt-get update && sudo apt-get install -y usb-modeswitch usb-modeswitch-data
3

Tell it how to switch modes

This little config file is the recipe that switches the modem from WiFi hotspot to a USB network adapter:

sudo tee /etc/usb_modeswitch.d/12d1:14db << 'EOF'
DefaultVendor=0x12d1
DefaultProduct=0x14db
MessageContent="55534243123456702000000080000c85010101180101010101000000000000"
NoDriverLoading=1
EOF

That creates /etc/usb_modeswitch.d/12d1:14db.

4

Make the switch happen automatically

A udev rule runs that switch every time the modem is plugged in, so you only have to set this up once:

sudo tee /etc/udev/rules.d/70-qmi-to-rndis.rules << 'EOF'
SUBSYSTEM=="usb", ATTRS{idVendor}=="12d1", ATTRS{idProduct}=="14db", RUN+="/usr/sbin/usb_modeswitch -v 12d1 -p 14db -c /etc/usb_modeswitch.d/12d1:14db"
EOF
5

Reload and reconnect

Reload the rules so the system picks up what you just added:

sudo udevadm control --reload-rules
sudo systemctl restart ModemManager

Then physically re-plug the modem so the new rule fires:

  1. Unplug the modem.
  2. Wait about five seconds.
  3. Plug it back in.
  4. Give it 30 seconds to switch modes.
6

Get an IP address

The modem is now a USB network adapter, but it still needs to ask the carrier for an address. This can take ten or twenty seconds:

sudo dhclient usb0
7

Check that it worked

Confirm the interface has an address and can actually reach the internet:

# Check the interface exists
ip addr show usb0

# Test the connection
ping -c 4 google.com

If usb0 shows an IP and the pings come back, you're online — that's it, the modem is feeding the Pi over USB.

Troubleshooting

The modem isn't detected

  • Check the LED is on. If it's dark, try a different USB port.
  • Give it a full 60 seconds after plugging in before deciding it's dead.
  • Try a USB 2.0 port rather than a 3.0 one — some of these sticks are fussy about it.
  • Make sure the SIM is seated properly.
  • Confirm the Pi can see it: lsusb | grep 12d1

No internet after setup

  • Double-check the SIM has an active data plan.
  • Your carrier may need a specific APN — set it if the default doesn't connect.
  • Open the modem's web interface at 192.168.1.1 to check its status.
  • Look at signal strength — you want at least a couple of bars.

No usb0 interface after the switch

  • Check the vendor and product IDs: lsusb | grep 12d1
  • Try the switch by hand: sudo usb_modeswitch -v 12d1 -p 14db -c /etc/usb_modeswitch.d/12d1:14db
  • See what the kernel logged: dmesg | tail -50
  • If ModemManager is fighting you, stop it: sudo systemctl stop ModemManager

The interface is there but there's no connection

  • Ask for an address again: sudo dhclient -v usb0
  • Check the routing table: ip route
  • Restart networking: sudo systemctl restart networking

Good to know

Networks it supports

4G LTE, 3G WCDMA, and 2G GSM, switching between them automatically.

Web interface login

Usually admin / admin — check the label on the device to be sure.

Power draw

Around 2W on average (roughly 500mA at 5V).

What the LED means

  • Solid — connected to the network.
  • Blinking — still searching for a network.
  • Off — no power, or a problem with the SIM.

Next steps

With the Pi online, you can carry on with the rest of the setup:

Flash your Pi in ~10 minutes

The Aircast Flasher downloads the image, sets Wi-Fi and hostname, and verifies the card — no terminal.

Download the Flasher