According to TPLink, their 3G/4G mobile router will connect to a usb cellular modem and route access through ethernet. They also claim that you can download non-standard binaries for modems, generate the firmware and upload to the TPLink router. Of course, the link they provide has no binaries listed.
I am trying to get a TPLINK 3020 to use my AT&T Wireless Hotspot to provide failover cellular access in case Comcast Business (my wired provider) goes down (like they do every other week or so).
