I have been experiencing this bug way too much for the past 2 months and it appeared only if I connect to a network for too Long through my wifi, I simply can’t connect to Xbox live thus unable to play with friends. I have come to the conclusion that it must be some network issues regarding minecraft and not my iOS device or my wifi network according to a network engineer who posted a similar issue on Microsoft help forums a while ago. So please fix this since it is your part and nothing else is causing this. The settings page also mentions “oops, your minecraft Xbox live has been disconnected recently and to restart the world” but even after doing it, it refuses to correct the issue. 

some other people experiencing the issues:

https://answers.microsoft.com/en-us/xbox/forum/all/cant-log-in-to-xbox-live-or-minecraft-pe-on-ios/7f71ea8d-1b60-4433-ad00-2c94bf85f26f

https://answers.microsoft.com/en-us/xbox/forum/all/error-with-ios-ipad-minecraft-login-something-went/9de62c81-7a21-4c3c-bf21-32e16ba48ac4 (please refer to Davidcata reply in this thread for better understanding of this issue, thanks)