Error 1722 is a Windows error meaning "The RPC server is unavailable.". This means the machine could not reach the target DC.
Error 1722 is usually an environmental issue. The most common causes are problems with the network itself, or the blocking of data traffic by a firewall.
Check that the the Remote Procedure Call (RPC) service shows as 'Running' within Windows Services. If the service is running and you're still encountering the error, there's most likely an issue with your firewall configuration.
1. From the affected machine, check to see if the RPC Service is causing the problem:
2. Verify if there is a Proxy configured that is blocking the connectivity.
Reference articles for RPC not available error:
1. https://learn.microsoft.com/zh-cn/troubleshoot/windows-server/user-profiles-and-logon/not-log-on-error-rpc-server-unavailable
2. https://learn.microsoft.com/en-us/troubleshoot/windows-server/identity/replication-error-1722-rpc-server-unavailable
3. https://theitbros.com/error-1722-the-rpc-server-is-unavailable/
