This was the exact process I used. I did not need to use cpstop/cpstart.
1. Backup both gateways
Take backups and snapshots. Save to external location.
2. Disable the interfaces from Solarwinds Monitoring.
3. Edit the Cluster object in SMS
Go into Cluster member tab, change the IP addresses for both cluster members to the new IP addresses.
4. Perform a SIC test in SMS to ensure comms to/from both gateways function as expected.
SIC was working fine.
5. Update the Alias URL (Platform Portal URL) within Smart Centre.
1. Place the new URLs in manually for each gateway.
6. Push an blank/empty Policy change to the firewall cluster in SMS
7. Change the Management IP address of the gateway in GAIA
Update each gateway to the new management interface in CLISH
Update the DNS host file entry for the firewall hostname/IP mapping:
8. Check ID Awareness PDP to ensure the firewalls are still connected to ID sharing peers:
pdp connections pep
pep show pdp all
Perform validation testing