On Kindle Fire, when connecting to Realms it gives an error “you must authenticate to Microsoft Services.   I have relogged, signed out and back in, rebooted, power cycled, and “all the things.”  

The devices are a pair of Kindle Fire HD tablets, one for each daughter.  They have played on our realm  with these tablets for almost a year without issue.  However, on Saturday, 01/23/2023, both tablets stopped working with realm at the exact same time.  

Their accounts both work on Xbox.   

Ive tried installing the XBox app on both tablets, and signing in and out to that app, just to see if perhaps that could work out the issue.