I have an old Raspberry B (with Raspbian Buster OS inside) and a 3G USB dongle Huawei e3276s-920 modem laying around in my closet. Let's try to install the modem and connect to internet. First, install modeswitch sudo apt- get install usb_modeswitch Then check is wether my modem is recognised by the Pi. Plug the modem to usb port on the Pi, and from terminal: pi@oldraspi:/var/log $ lsusb Bus 001 Device 004: ID 12d1:14fe Huawei Technologies Co., Ltd. Modem (Mass Storage Mode) Reboot the Pi with usb modem still plugged in, and again launch this command: pi@oldraspi:/var/log $ lsusb Bus 001 Device 007: ID 12d1:1506 Huawei Technologies Co., Ltd. Modem/Networkcard Note that 12d1:14fe before reboot and 12d1:1506 after reboot. Edit /etc/usb_modeswitch.conf , add following lines to the end of the file: DefaultVendor=0x12d1 DefaultProduct=0x14fe TargetVendor=0x12d1 TargetProduct=0x1506 MessageContent="555342431234567800000000000000110620000001000