im using an Raspberry Pi4 with latest openWRT. My Provider Modem is on LAN Port and i use an TPLINK Usb to Ethernet for LAN -> to my Switch.
Currently if have no internet and want to build something like an 4G / LTE Failover. I found several 4G Modem USB Sticks. Is it possible to ad one of this to my raspberry pi4 and configure it as failover ?
The modem will need to be in the appropriate USB mode so that the kernel modules can use it. So, it depends on whether the particular modem you have is already in that mode, or at the very least, configurable (you may need to do some setup via AT commands to the modem before plugging it in). Common kernel modules are qmi-wwan and cdc-mbim, but there are others. Also, these kernel modules will need to be in your firmware, along with the requisite USB support - you can either compile them in or install them via opkg. Finally, you need some sort of control software for the modem so that it can be configured and connected.