MCPE for iOS unable to connect to world error

i have been playing with another player for several weeks connecting to each other's worlds through Xbox gamer tags.     3 days ago we started experiencing the unable to connect to world error message.  We have tried numerous troubleshooting tips with no luck.  We both have iPads.  Please advise is there a know issue with the MCPE server?   This is very frustrating any help or assistance would be very much appreciated