About WiFi connecting issue

Since I have updated the new version for my phone, my WiFi connection stop transmitting signal after I connected it for a short time, like 1 minutes, but the signs of WiFi signal still saying it’s “full”, have signal. But I cannot load any pages, feeds. I’ve tried to reset all network setting, and seek help in Genius Bar, it’s seems to be fine when I connected to the apple store WiFi, once I backed home, this happen again. I’m not sure it’s my phone’s problem or my router’s, because other devices do not appear with this problem, their connection is good. I want to ask what wrong with my phone. Thxxxxx