AT&T Update to Marshmallow

[Crashinator]

Recently update my AT&T M9 to Marshmallow and now I'm having difficulty connecting to my home WIFI. It either is very slow to connect or I have to re-enter my password to use my WIFI. I have no connection issues with other WIFI hotspots.

Any ideas what's going on?

 

[GSDer]

Have you tried removing that SSID and re-entering the information?
Did you perform a Factory Reset (along with a system cache wipe) after the update?