I have a Huawei E3372 USB 4G dongle and have it configured as my primary WAN in MWAN3 with a DSL backup on an Archer C7 router running OpenWRT 18.04.
It's worked well up to a point however lately, the 4G dongle keeps losing packets forcing MWAN to switch between the two frequently and causing MWAN to switch between the two frequently and disconnecting the local clients. It has to lose 8 sequential pings for the connection to be deemed as down so it takes more than just one or two hiccups.
When I connect the dongle to my computer directly, I see zero packet loss even after running ping for a while.
What might be causing this issue and how can we get this dongle working on an OpenWRT router as well as it does when plugged into a computer?