Cant join my friends world and they cant join me either but I can join my other device that is connected on my wifi how can I fix this!

S when ever I am trying to join my friends world I cant joined them it just stays regenerating world for 10 minutes and then it says unable to connect to world and they cant join my world either.i think it might be that I can play with devices connected to my wifi if it is I dont know how to disable that.pleas help!

This happens with my 2 devices