This is a chassis specific device...you have to subscribe to their "hot spot". Likely, Airstream is listed for their B-van as they have it built into the Mercedes chassis as they order it that way. This is more a question for Ram.
But right BELOW that, it says if your brand is not listed you can get the spark.
https://www.att.com/devices/harman/s...sku=sku8900265
Looks like a device that plugs into the OBD port me.
ALSO, if you go to the Winegard site.
Winegard ConnecT RV Internet — winegard.com
They say right on there that the ConnecT2 can connect to 4G LTE. It says it is compatible with Verizon AND AT&T.
So who has told you that the COnnecT is not AT&T compatible?
PS. My guys have been calling and leaving messages for a service appointment but have not gotten a response.