I do realize this could be caused by many different apps, however I ran a system update on my ATT Samsung S5 Active last night and I keep getting a white box that pops up with "Connection Failed. The connection has failed. Reconnect? No Yes

Neither option has fixed the problem nor has resetting my phone or powering it down. Anyone else have this issue from the update?

My wife has a Galaxy S6 and we've had multiple issues with AT&T after updates have occurred. We have not had this specific problem, but we've had others. We are very close to riding out our contract until it won't cost us an arm and a leg to terminate it and switching to some other provider - maybe Verizon (?). AT&T seems to only care about iOS as we have taken our Android phones in several times and gotten literally no service and/or help from them.

Root, crack, custom recovery, custom rom, problem solved.

I ended up factory resetting. Worked great.