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"The RPC Server Is Unavailable" (0x800706BA)? It's the Dynamic Port, Not Just a Service

Published June 10, 2026 · by The FixHub Team

You get “The RPC server is unavailable” (0x800706BA / RPC_S_SERVER_UNAVAILABLE) using remote management — services.msc against another machine, remote WMI, network printing, Computer Management, or remote registry.

Why “restart the RPC service” misses it: the common advice is “restart Remote Procedure Call” or “disable the firewall.” But the usual real cause is the client can’t reach the dynamic port. RPC works in two steps: the client contacts the Endpoint Mapper on TCP 135, which replies with a high ephemeral port to use — and if that ephemeral range is blocked by a firewall/NAT, you get 0x800706BA even though port 135 itself is open and the service is running.

Fix 1: Confirm the basics are running

On the target machine, ensure these are Running / Automatic: Remote Procedure Call (RPC) (RpcSs) and RPC Endpoint Mapper (RpcEptMapper). Don’t disable them — RPC is core to Windows.

Fix 2: Open TCP 135 and the dynamic RPC range

On the target’s firewall (and any firewall/NAT in between), allow:

  • TCP 135 (Endpoint Mapper), and
  • The dynamic RPC range (default 49152–65535 on modern Windows).

Quick test from the client with PortQry or PowerShell:

Test-NetConnection <target> -Port 135

If 135 connects but operations still fail, the dynamic range is blocked — open it.

Fix 3: Pin RPC to a fixed port range (firewall-friendly)

If you can’t open the whole ephemeral range, restrict RPC to a narrow band on the target. In regedit:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\Internet

Set Ports (e.g. 60000-60020), PortsInternetAvailable = Y, UseInternetPorts = Y, reboot, and open just that range on the firewall.

Fix 4: Rule out name resolution and the network

  • Confirm the target name resolves (try the IP instead of the hostname).
  • Make sure both machines are on a reachable network and the target is actually up. A bad DNS/NetBIOS answer surfaces as 0x800706BA too.

FAQ

Why does it work locally but not remotely? Local RPC doesn’t traverse the firewall; remote RPC needs TCP 135 plus the dynamic port open. That gap is the classic 0x800706BA.

Disabling the firewall “fixes” it — so it’s the firewall? Yes, but don’t leave the firewall off. Open TCP 135 + the RPC range (Fix 2) or pin the ports (Fix 3) instead.

Sources: Microsoft Learn — Troubleshoot “RPC server is unavailable” errors