If the hostname is changed for a machine with Veeam Backup & Replication installed the console may fail to open with an error, shown in the following screenshot:
The Veeam Backup service will be stopped. Attempting to start the Veeam Backup service results in the issue shown by the following screenshot:
Logging will show the Veeam Backup service attempting to connect to SQL using the previous hostname. %programdata%\Veeam\Backup\Svc.VeeamBackup.log:
Info [DB] Connecting to SQL Server (CurrentUser=[NT AUTHORITY\SYSTEM], ServerInstance=[<OldHostname>\<SQLInstanceName>], Options=[Direct])
Info [DB|ERROR] Failed to connect to server.