Wifi authentication error, how can I fix it?

[AC Question]

wifi authentication error

Galaxy 10.1 model GT-N8013 Running version 4.1.2. No problems for 3 years. Placed tablet on charger in AM. In PM noticed that lock screen had changed with no input from me and it would not connect to wifi. Rebooted tablet, rebooted router, cycled wifi, cycled bluetooth..... I am at a loss. Believe problem connected to same cause as lock screen change. Anyone??

 

[AlphaTango414]

Re: wifi authentication error

Does anybody else have access to your network?

Have you tried connecting a different device to the network?

Have you tried connecting to a different wifi network with the tablet?