Samsung tab A disconnected itself from the WiFi and won't reconnect.

Question

Hi, This evening my Samsung tab A disconnected itself from the WiFi and won't reconnect.
Other device have not lost their wifi connection and are still using the Wifi without issue.
This is the troubleshooting I have tried: 
Moving the tab A into the same room as the modem, 
restarting the tab A, 
turing the tab A off for a minute then turning it back on, 
re-entering the wifi password, 
deleting the wifi network and then re-adding it, 
turn off the modem for a minute then turning it back on, nothing seems to work.
In the top right corner of the tab A there is no wifi icon.
If I go to "Settings", "Wifi", I see the tab A see the network. The network has full wifi bars. It has under the net work name (Authentication error occurred).  When I go to "Manage network settings" it has the word (Unchanged) under Password. I then click "Show password" but it still says (Unchanged).
I retype the password and click save, it goes back to the wifi screen but doesn't connect, I check the password and it is back to (Unchanged).
I look forward to hearing from you and getting this sorted :)

Jinane Karhani · Answer

Hello, check these few steps:
- do you have anti-virus? if yes remove it & restart it.
- install wifi fixer application & restart the phone.

Huston · Answer

Hi Jinane Karhani,

I do not have an Anti-virus installed.  How can I install an app called "wifi fixer" if I can't connect to the wifi?  I have a Samsung tab A not a phone. 

Any other  ideas?

sara · Answer

hi,

between the deleting the wifi network and re- adding it, did you restart the tab a?

Huston · Answer

Hi Sara,

Yes, I have deleted the wifi network and re-added it, as well as restarting the Tab A, both several times.  If you read my original post, you will see that is one of the things I have already tried.

Any other suggestions?