Error message that keeps showing up on my fire tv and regular smart TV. Join "CoxWiFi." Why am I seeing this page? Your request has been identified as potentially malicious, and access has been blocked.

Doesn't Amazon sell Smart TV sets built on the Fire TV OS?

It'd be beneficial if OP posted makes and models but since "Fire" is festooned throughout the post, I assume everything has the Fire TV OS.  There may be a way to force into the OS...such as holding the Power button...to remove CoxWiFi as the network ID.

The link I posted reads the Fire TV (OS) needs to be activated before operation...even operating via an antenna.  I agree the TV were operational beforehand, but for some reason the OS keeps losing its authentication.