Hi again!! I got a smashed s4 in ebay. I tried to detach the bottom wifi connector. Signal went just a little worse. About the same. I saw in the link above that the antenna is in the bottom back part. I perhaps think it was faulty. Maybe moist, dirt, water or??? Anyway i clicked both backcovers off and switched them. NOW WIFI IS FINE!! PERFECT LIKE ALL MY ITHER PHONES!!. SO IT HAS TO DO WITH THE ANTENNA I SIDE THE BACKCOVER BOTTOM. Regards lis