[REALMS-5953] Error 500 when connecting to realm

I have been using my realm with no problems for a long time but suddenly the world I have been working on will not open. I can open another world, but when I switch back my main world will not load. Message; Realms (500) Could not connect to realms. Tried multiple times over several days, not working. Internet connection is fine. I have turned off firewall and anti virus to see if this helps. No change. Please could you advise. Many thanks.

Game output

03:18:50.495
Couldn't connect to realms
Realms (500) Could not connect to Realms: Connection reset
	at dsy.a(SourceFile:436)
	at dsy.i(SourceFile:201)
	at dst$1.run(SourceFile:531)
03:19:57.853
Couldn't get pending invite count
Realms (500) Could not connect to Realms: Connect timed out
	at dsy.a(SourceFile:436)
	at dsy.k(SourceFile:325)
	at dsy.j(SourceFile:320)
	at dun.q(SourceFile:216)
	at dvu.run(SourceFile:32)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
	at java.base/java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305)
	at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:833)