S6 won't find and/or connect to WiFi that is has been connected to in the past

[AC Question]

I have a TP-Link router with a 5GHz Wi-Fi setup without broadcasting the SSID. My S6 was connected to this network from June 2015-November 2015 with NO issues at all. I went on vacation for a few months and when I came back, my S6 will no longer connect to this network. My iPhone 6 in the same scenario, picked the network back up and it is working fine on it, so I don't think it is the network or Wi-Fi settings.

I have tried:
-Changing non-broadcasted SSID network password and SSID to something new. No Love.
-Broadcasting the old and new SSID (the S6 will not see broadcasted SSIDs, but other devices do and connect normally)
-Broadcasting the 2.4GHz network. Same issues as above.
-Connecting to the 2.4GHz network while not broadcasting SSID. No Love.
-Restarting phone and router multiple times

 

[jersno]

I have also used a third party Wi-Fi app (WiFi Manager) to forget the network (and all old networks) from my phone. I then re-added the hidden SSID network and still no love.

The phone sees many other WiFi networks, but not either of mine when broadcasted.