This was a very old bug since Aquatic Update. The game crashes everytime I open it when signed in tk Xbox. or turning on Wi-fi while playing and signed in to xbox.
It's a very annoying old bug making the game very unplayable.
It usually happens when signed in to xbox with wifi open.
Crash frequency: Very frequent, unable to open minecraft (when on wifi)
Related issues
Comments

Thank you for your report!
We're actually already tracking this issue at MCPE-29021, so we will resolve and link this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.