Wireless Joint

Well, I bought a pre owned M1 from Mercari last night and hopefully its not black listed, their policy states that if the product does not work I can receive a refund on the product... hopefully I made the right decision.

So I am currently on a AT&T plan the "AT&T Unlimited Plus Multi Line Plan" and the current router that I have is the Mf279, im looking to upgrade to a better hotspot router and im having trouble finding everything I need to be looking for. (I was told this would be the place to get...