you can t grantee all windows servers will work after in place upgrade
in such cases , if you have high- availability servers (e. g. more than 1 console server ) , its safe to do :
-take backup
-remove one one of the nodes from load balancer
- re-build it with new OS
-do UEM installation and patching with same old version (e.g console , DS, ENS. ACC,.....)
- return it back to load balancer
-repeat to the remaining