To create a rule that allows inbound network traffic to the RPC Endpoint Mapper service
- On MBRSVR1, in Group Policy Management Editor for your server GPO, in the navigation pane, right-click Inbound Rules, and then click New rule.
- On the Rule Type page, click Custom, and then click Next.
- In the This program path text box, type %systemroot%\system32\svchost.exe.
- Next to Services, click Customize.
- Click Apply to this service, select Remote Procedure Call (RPC) with a short name of RpcSs, click OK, and then click Next.
- On the warning about conflicting with Windows service-hardening rules, click Yes.
- On the Protocol and Ports page, for Protocol type, select TCP.
- For Local Port, select RPC Endpoint Mapper, and then click Next.
- On the Scope page, click Next.
- On the Action page, click Next.
- On the Profile page, clear the Private and Public check boxes, and then click Next.
- On the Name page, type Allow RPC Endpoint Mapper, and then click Finish.
Or: netsh advfirewall firewall add rule name="Allow RPC" protocol=tcp service=rpcss dir=in action=allow profile=domain
Source: https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/cc732839(v=ws.10)