This has been happening to me too after 1.16.1 i believe was the update. I tried taking my vpn off and using a device that never had a vpn on it, switching to data, deleting the minecraft app and reinstalling it. Logging out of my microsoft account and logging in on another and still unable to access it. I own the realm and i cant even log on. Sometimes I can get in by persistently trying to enter it and eventually I can get in and dont disconnect or lag at all (making me think it isn’t actually connection issues) but this can take 30 or more minutes of failing to load in just to finally access it. Just today it took me over an hour of trying to access it before i gave up and came to check if anyone else had these issues.
This is happening to me too. Just paid for a brand new 10+ player realm and cannot see chat messages sent by other players. The only difference is that even after hours messages are not received. I have another realm opened back in 2019 and messages as of yesterday (when I was last on) were working perfectly fine. On the new realm (the one with the problem) I can see messages I send but they are not received by other players at all. No one has chat muted at all. We can communicate instantly using /w or /say but it is very inconvenient for everyone, and being an OP on the server it fills up your screen very fast as each message with /w is received twice.