Azure Site Recovery Hyper-V host Disconnected

MS provides a troubleshooting document

https://video2.skills-academy.com/en-us/azure/site-recovery/hyper-v-azure-troubleshoot

but your case is not defined under this document

I assume your connection between hyper-v and Azure Storage Blob is healthy

and all hosts are compatible with the requirements

the problem can be related with

Azure Recovery Services Agent and Microsoft Azure Site Recovery service

@Ranjit Singh Thank you for reaching out to us on Microsoft Q&A platform. Happy to help!

From the information you provided, I understand that you have 3 Hyper-V hosts and one is in disconnected state.

Also, you mentioned that all the VMs associated to this host are showing health status as "Critical". Is replication of these VMs happening correctly or the replication is failing? Few suggestions to follow:
Please ensure the connectivity to required URLs is not getting blocked in the firewall/proxy and also check if there is any rule enabled to allow these URLs for a specific time period. Source: https://video2.skills-academy.com/en-us/azure/site-recovery/hyper-v-prepare-on-premises-tutorial#required-urls

Check if there are any certificates expired. If yes, please renew it. Check if Azure site recovery provider installed is a latest version. Reference link - https://video2.skills-academy.com/en-us/azure/site-recovery/service-updates-how-to#hyper-v-vm-disaster-recovery-to-azure Go to site recovery infrastructure > Hyper V hosts > add server > select the configured Hyper-V site> Download the vault registration key > copy it to the VMs in question > Launch DRAconfigurator.exe > Reregister the host using the downloaded registration vault key Post registration > hosts should return to Connected state. Hope this helps. Let us know how it goes!

@Ranjit Singh Just checking in to see if you got a chance to see my response and if it helped, I would request you to "Accept Answer and Upvote" so that the relevancy of this post will improve when anyone in the community search for a similar query.

@Ranjit Singh We haven't heard back from you. Please reply if you have any questions in this matter and we will gladly continue the discussion.

@SadiqhAhmed-MSFT Hi, thank you for your reply. All other connected Hosts uses same Firewall rules so this is not the case as it was connected before and all of a sudden disconnected. It happened to one of the other host earlier as well and I just removed and re-added which resolved the issue but couldn't find the root cause. Now that it has happened again, I want to know the root cause. I checked the agent and certificate are up to date.