Realms are garbage my friend created a realm a few months ago and ever time it came up with the same error message after trying everything I connected customer support in my email I said what the problem was blah blah and I had check all the faq and trouble shooting after a week I got a human response saying check the faq……. So I told them I had done so multiple times as they may have missed it in my original email then a week later I was told to double check…….. The realms support is a joke and realms don't even work. Untill last weekend when my friend made a new realm for the first 2 days everything was fine we mapped out the world on Saturday then it crashed and reset the world which was annoying because we spend about 6-7 hours mapping the world out then on Sunday we gave up mapping and just started the world however it was constantly laggy then after 5 hours of play it crashed and I got the same error and now over 10 hours is waste realms is a joke and shouldn't even be a paid service if I'd doesn't even work and if it does its laggy mess
Source: https://www.reddit.com/r/Minecraft/comments/lfepb1/lets_talk_realms/