Not sure if anyone else have seen this but if I had a nickel for every time it happened, well it only happened twice, but still. Upgraded DDC environment from 2203 to 2402 and the BrokerService.exe.config and HighAvailabilityService.exe.config settings had to be modified from this article. https://support.citrix.com/article/CTX584038/citrix-delivery-controllers-generates-event-id-505-and-event-id-3602-continuously

Same happened to me when upgrading to 2311. My VDAs went unregistered after 2 hours so we decided to reinstall the DDCs.

I'll do a full writeup on what we did to fix it. and post it.

perfect! Modifying the config file made things worse for me..

I had the same issue when going to 2311 and the article fixed it.