Lost wifi connection on Android

[#1]

My Android tablet has lost the connection to my wifi.  It finds the network with excellent signal strength, but when I enter the router password, it reports 'Authenticating'.  After a while it closes the app but does not connect.  I have entered both the router password and tried the Wireless Key, but neither appear to solve the problem.  I have two other android devices, fortunately they will connect without any problem.  Where is the fault and what can I do about it?

[#2]

First thing to try is forgetting the Wifi network and trying to connect again. Normally you can do this with a long press on the network name and selecting forget network.

[#3]

Thanks.  That worked.