Can't login to game. Connection Error loop

I am on Android. My game will not allow me to login in. It is stuck on the splash screen saying Checking For Updates in the bottom corner. After about 15 seconds it pops up with an error window as follows

CONNECTION ERROR

UNABLE TO ACCESS REQUIRED INTERNET RESOURCE. POSSIBLE SERVICE INTERRUPTION OR POOR INTERNET CONNECTION. 

TRY AGAIN

The rest of phone, apps, music, YouTube, other games work just fine. I have gone through typical airplane mode, force stop, cache clear, uninstall/reinstall, network switch, network reset, etc. I did not get to participate in gac and so received no rewards, missed energy. Any help?