Can't Log onto Realm (Java Edition)

We're not able to log onto our Java Realm. There are 4 of us with access and we're all experiencing the same issue - after clicking 'play', we get 'connecting to realm' for a while, then the error 'An error occurred, please try again later.

 

I've tried closing the realm and re-opening it and shutting down Minecraft and re-starting it.