I've had a similar issue too, Johnathan Hansel's comment actually makes a lot of sense because I can see how the owner not getting the update could cause this issue.
I made my own report here:
https://bugs.mojang.com/projects/MCPE/issues/MCPE-22157?filter=allopenissues
I would contact the owner of the server to let him/her know that they need to update.
Do we need to reinstall Minecraft?
So realms is completely fixed and accessible now?
Yeah I forgot to included those, I'm trying to find an email for 4j right now to get in contact with them, although they more than likely are aware of the issue already.
UPDATE: I meant to get in touch with 4J Studios not Mojang, the issue still stands, the only thing I can suggest to everyone right now is if you have a twitter account, tweet @4jstudios with this message:
"@4JStudios There is a big issue with PE realms at the moment and nobody can connect to realms https://t.co/kN3eKsbYBQ please help 4J" the link leads here, if enough people tweet at them then they should see it.
Hello, I would like to make an addition to this bug. I had the same issue where I got stuck on the loading screen, and this also affected servers as well as my own realm. I reinstalled Minecraft and tried joining a server again and, as expected, I got stuck on the loading screen again, except this time there was text over the background that said "Syncing pack with server, please wait." I waited for a little while to see if it did anything but it never did anything else. There was an update to MCPE after I reinstalled the game, the issue was already there before the update. I am a beta tester of MCPE and have emailed Mojang regarding this issue, and I would advise anybody who is reading this to do the same.
This issue is with more than 1 server it's effecting different hosts which is clearly an issue with the game. I have been in contact with the owner, i'm pretty sure he would have downloaded the update already, this also suggests that there is an issue withe the game, and the servers that do work are very laggy. But since you want to completely dissmiss this and mark it as invalid without even looking into it, i'll just get hold of 4J however I can instead, but thanks for wasting my time, I kind of expected this.