I used a Huawei E5377 via USB for over 2 years without issue on both OpenWRT and LEDE. It will appear as an Ethernet device when configured correctly. You have to install a few kernel modules and then add a few rules to trigger on the device ID.
Things may have changed in the past 18 months, but from my now-cryptic setup notes:
opkg update; opkg install usb-modeswitch kmod-usb-net kmod-usb-net-cdc-ether
(plug in device)
cat /sys/kernel/debug/usb/devices
(find the ID?)
vi /etc/usb-mode.json
Add: "55534243123456780000000000000a11062000000000000100000000000000" to message array
Search for the line with "1f01", then add a new section following:
"12d1:1f02": {
"*": {
"t_vendor": 4817,
"t_product": [ 5340 ],
"mode": "HuaweiNew",
"no_driver": true,
"msg": [ ]
}
},
usbmode -s
cat /sys/kernel/debug/usb/devices
Check for eth2 in dmesg
Add eth2 to the WAN interface, make sure it doesn't appear elsewhere (i.e. not in br-lan)
Add LED trigger (Archer C7):
tp-link:blue:wan
netdev
eth2
link transmit, receive