KB1198: NFC connectivity troubleshooting steps
https://www.veeam.com/kb119826.08.2011 · The cause of most NFC errors fall into 3 primary categories: DNS (The proxy or Veeam server cannot resolve the ESXi host) Port (902) (The proxy can resolve the IP, but port 902 is blocked) Permissions* (The account specified in [Backup Infrastructure] for the vCenter does not have permissions)