Q: Ipad Version A1460 32G Wifi Issue

Like in the title, i bought it in summer 2013, it have issue like this: sometimes it show that Ipad connected to Wifi but when i use Safari or Appstore it tell me i don't have internet connected, when i tried forget Wifi and re connect then it work absolutely fine. It happen since ios 7 i though it was ios issue but now at ios 8.4 it still happening,i don't think that is modem issue because i have iphone 4s i bought before ipad, and it never run into issue like this, had same wifi adress, same ios 8.4 as ipad. Thank you if you can help me fix this small issue. It don't bother me but if possible why not fix it? Right?