Internet gone for everything except Skype and FB Messenger

[AC Question]

So I've had this problem for a day and a half now, and it's really annoying. My phone is connected to a WiFi network, and yet no app has an internet connection, be it Facebook, Youtube or the Play store. The only two apps who still work somehow are Skype and Messenger (albeit not always, sometimes it takes a minute or so to send a message). I have no idea what the cause of this problem may be. I tried a few things from some Youtube tutorial, but they did not help.
Hopefully you people will have the answer