It will not let me join any servers

So at first it would not let me join any servers but I checked the play store in then it said update so I updated it and it still won't let me join any severs I can not even join my friends which I'm sad about and I know its not my wifi because the market place works fine please help me I want to go on severs again oh ya and one more thing when I try to join a message will pop up saying (unable to join world) I will appreciate that yall fix this and I know many people get this bug too thank you for listening to my problem and bye.