Can I change the IP address of Linux or Windows devices that run the Nanitor Agent?

Yes, that is fine because there is only one way communication between the Nanitor Agent and the Nanitor Server. The Nanitor Agent connects to the Nanitor Server on port 443. As long as the FQDN of the Nanitor Server is not changed and the new network configuration can still access the Nanitor server you will not have any problems.