Fix: Veeam Failed to check whether snapshot is in progress (network mode). The RPC server is unavailable. Code 1722
Whilst migrating some service roles from Windows server 2008 R2 to Server 2016 I noticed that the Veeam backups of the new servers were failing with the error Failed to check whether snapshot is in progress (network mode). RPC function failed. Function name [IsSnapshotInProgress] Target Machine [MachineName] RPC error. The RPC server is unavailable. Code 1722.
It seemed likely this is a firewall issue, and it turns out it was.
It was pretty simple to resolve once I knew which firewall to enable. Enable the rule Remote Service Management [RPC-EPMAP]. This will allow the job to continue. This rule is disabled by default in server 2016.