iPhone 6 can't connect to WIFI anymore

Ok, since my iPhone 5 has been updated to 6.1, it can't connect to WIFI networks anymore and from time to time restarts for no reason.

 

I tried to restore from iTunes, and now I wan't to back it up from iCloud, which can't happen without WIFI.

 

Can anyone help me with this issue?

 

Thanks in advance!

View the original article here