Wifi issue with game apps

Hi, does anyone know why my online games fail to connect when wi-fi is on? Only games are affected. YouTube, Twitter, Facebook etc. all fine. Only games that require online connection fail. For example, mario run, candy crush, the new sonic racing game from apple arcade. None of these games connect when wi-fi is on but will connect via mobile date if i switch wifi off. I have done a network reset and issue still remains. IOS 13