It seems I'm facing a strange problem with my smartphone.
After the last update, I can't connect to my office's wifi. All the other devices connect normally. However, I tried resetting the router many times. 
On the other hand, my phone connects perfectly to all other networks. I think I did everything possible, even a hard reset, but the problem insists.
 I've tried changing the IP settings to static and typing my IP etc, but nothing worked.
Any other ideas are welcome. 

thanx

Update : When I walk 15 meters away from my desk to another office and try to connect again, my phone connects normally to the same network but from a different router. So, I suppose the problem is between my nearby router and my phone. Is there any way to fix this? It worked till last Friday, so there's no chance of incompatibility.