i cant join my friends world "unable to connect to world"

i can join sometimes ,but not enough for me not to not seek help.

when i try to join my friends world it doesn't let me get past the fire wall "unable to connect to world".

I've tried a lot of stuff and it still doesn't work

pleas don't give me a bot to come back with help it will be useless 

Thanks minecraft

 

RascallyChimp62