Iphone 5 slow wi-fi after update to ios8

My iPhone 5 has a slow wi-fi speed or not working at all after upgrading to ios8. My other apple devices including a iPhone 4s works normal. Also the pc from which i am typing now has no problem with the wi-fi. I try-ed to reset to network settings but still the same. When i try to run an internet test with the "speet test" app, it says Latency Test Failed...

Anybody in the same pain as me?

Thanks!