Hey @MojangSupport, when me and my kid try to connect to our realm we suddenly get this error. I've restarted the router and updated Java. We're running Windows 10 and Linux Mint. However, connecting to others realms do work without problems.

I now tried changing the realm to another slot with a random adventure in it, which I could connect to. I then switched back and could connect to our normal world. However, it had reverted a bit to an earlier stage and a few things we had built were gone. Not much. Corrupt save?