Can't log in to Fortnite on my sons Xbox. Just says "an unexpected error occurredwhile...

I have been trying to log in to Fortnite on to sons Xbox but keep getting the above message and won't load into game.

I have tried the restart options and several things that searched on community but still no luck.

I've tried changing network settings, swapping wired to wireless etc

I've removed and re-signed into microsoft Accounts

And still no joy

Please help

:)