its saying it can't find the proxy to get internet, first thing is to reset the cable/modem/router ie switch it off for 30secs
you could have 2 devices on the same ip etc. its worth resetting these every few weeks anyway. The tablet will be on another ip and might have its table OK so it still works.
if after this it does not fix it the local hardware could be failing, I just replaced the network card on my son's PC as it went recently. it was integrated into the motherboard, just brought a addin card for £10 going fine now