> For the complete documentation index, see [llms.txt](https://help.security.gallagher.com/knowledge-hub/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.security.gallagher.com/knowledge-hub/deployment-resources/support-tools-and-troubleshooting/network-testing-and-troubleshooting.md).

# Network testing and troubleshooting

Test controller communication and configure DCOM for restricted networks.

### Test port 1072 with Telnet

When ports are restricted, a controller can ping but remain offline. Port **1072/tcp** must work in both directions. In v8.50+, only controller outbound access is required.

* **Failed:** `TELNET <FTC IP> 1072` shows a connection failure.
* **Successful:** Telnet returns a blank screen or connected status.

### Test connectivity with PING

Run `Ping <FTC IP> -t`. Ensure the FT Controller can ping the Command Centre Server continuously. Routers and firewalls on the path must pass **ICMP**.

### DCOM communication failures

DCOM uses **TCP 135** to establish sessions. It then uses dynamically assigned high ports. Firewalls can block those ports after the initial connection.

**Symptoms:** The client connects initially, then disconnects. Event Viewer logs `DCOM error` messages. The client cannot reconnect. Failure can also be partial rather than total — the client stays connected but receives no events or alarms, the Hardware window is blank, or Find does not work.

**Fix:** Configure a fixed DCOM port range. Open that range in the firewall. Allow TCP 135 plus the configured range.

> **DCOM does not work through a NAT firewall.** It embeds raw IP addresses in its marshaling packets, so the client must reach the server on its actual IP. No port configuration works around this. (Microsoft KB 154596.)

### Restrict DCOM port assignments

1. On the server, open **Registry Editor**.
2. Navigate to `HKEY_LOCAL_MACHINE\Software\Microsoft\Rpc\Internet`.
3. Add a `Ports` multi-string value. For example, use `5000-5100`.
4. Add `PortsInternetAvailable` as `Y` and `UseInternetPorts` as `Y`.

Restart the server. Open TCP 135 and the selected range. Use a range of at least 100 ports. Busy systems may need more.

**Sizing the range.** Budget at least **5 ports per concurrent client** — but that is the per-client basis, not the floor. Do not go below the **100-port minimum** above, even for a handful of workstations, and avoid ports other applications already use.

**Alternative method.** The same range can be set through `dcomcnfg` instead of the registry: **Default Protocols** tab → **Connection-Oriented TCP/IP** → Properties → **Add Port Range**. It is required on the **server**, and may also be required on **clients** because of callbacks — use the same range on both. (Microsoft KB 154596.)

### Other utilities

* **DNS/HOSTS:** Use a HOSTS file when DNS cannot resolve controller names. Add an `<IP> <HOSTNAME>` entry to the file in `%WINDIR%\System32\drivers\etc`, reboot to apply, then ping the host name in both directions.
* **Time Sync:** Intercom requires the client clock to be within **30 seconds** of the server. Check with `NET TIME`.
* **Robustel:** Configure external cellular modem IP settings through the modem interface.
* **C6000:** Verify link status and speed in the controller web interface.
* **Also useful:** `IPCONFIG`, `PING`, `NBTSTAT`, `ARP`, DHCP/BootP, Terminal Services, and VPN diagnostics.


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