iPHONE 4 16gb 02 working +

this is a working iphone 4, not blocked or fake. WI FI has stopped working after i updated to 5.1. internet works fine using the internet from your sim card but i cannot connect to my router for some reason. makes calls perfectly. feel free to test when meeting other than wi-fi phone is in perfect working condition with a new back and an unscratched front.