Greetings.
The 3.23 UCSM gui is HTML5 only.
Are you talking about trying to open the vKVM?
If it's the overall UCSM gui login, can you confirm you are trying with https:// ?
Can you SSH into the UCSM VIP?
If you can, run a couple of commands:
#connect local
#show cluster extend
#show pmon state
Thanks,
Kirk...