Is it possible to change the IP address of checkmk server

You would need to modify all rules where you have specified original ip address. For example in Agent Bakery, if you use it. And then re-register all servers again. If you use DNS everywhere in rules, should be fine, then just re-register servers.

I was moving our main instance from on-prem to cloud few days ago. And had to do all above things.

Flip the notifications toggle off during your work.
image