We are using a Nutanix cluster though this could just as easily apply to VMware. We use RDP sessions from a Windows 2012 server to thin clients running either Windows 8, 10, or HP ThinPro to provide HMIs in an industrial setting. Currently I have to schedule maintenance on our (infrequent) down days as my operators freak out if the RDP sessions drop even momentarily. We have noticed that migrating VMs often causes these sessions to drop.
Is there a way to configure either the thin clients or the server so that the connections could weather the perhaps several millisecond-long outage as the VM migration completes?
If the VMs are in a domain, configure GPO to allow clients automatically reconnect to remote desktops
computer configuration > policies > administrative templates > windows components > remote desktop services\connections automatic reconnect - ensure it's not disabled
configure keep-alive connection interval - this is very important if you are using a load balancer, whether software such as MS NLB or hardware
RD connection broker folder also has an important setting if you are using a load balancer: use ip address redirection