Although 1.16.1 was supposed to fix this problem, I still find that when I go to play in my friend's Minecraft Realm, it gets forever stuck on "Connecting to the realm." I know that this is an issue with these versions specifically because I was able to log into his realm no problem before he updated it.
This appears to be a duplicate of REALMS-3075, which hasn't yet been resolved. If you have any additional information to provide regarding this issue, feel free to comment on the parent ticket. If you feel that this issue is affecting you, feel free to vote for the duplicated ticket, to give Mojang a basic idea of how many people are impacted by the problem. Just to further inform you, this will not determine how quickly the bug gets handled or fixed.