Tablet to WiFi Problem with authentication

[1Achas]

I have a MiTraveler by Michley Electronics 10" tablet. I'm 20 feet from my WiFi router. I can connect sometimes and sometimes it just goes back and forth between obtaing ip address, etc and disconnecting. Sometimes it's a sold connection for hours at a time. Lately it's been coming up with "problem with authentication". What's amazing is, three others with this tablet have the same thing come up. This is almost not worth it. Any clues?

 

[PvilleComp]

Did you power cycle the router?

Also, have you noticed this problem connecting to other routers or just your home router?