WinDiscovery is blocked by Windows Firewall or endpoint security

Symptoms

• No devices are discovered on one PC, but devices are discovered on another PC connected to the same network
• Devices appear briefly, then disappear
• WinDiscovery stops discovering devices after a Windows update or security policy change

Causes

• Windows Firewall is blocking WinDiscovery UDP traffic
• Group policy (GPO) enforces firewall rules that override local settings
• Endpoint security software is blocking discovery traffic or preventing rule creation

Troubleshooting steps

1. Confirm the issue is PC-specific.
   If WinDiscovery works on another PC on the same subnet, the network and devices are likely OK, and the issue is local to the affected PC.
2. Test an approved WinDiscovery firewall exception.
   Have IT permit WinDiscovery traffic on the affected PC, then repeat discovery. If this resolves the issue, retain the approved application-specific rules.
3. Create explicit allow rules for WinDiscovery.
   Add inbound and outbound rules for WinDiscovery and allow the required UDP traffic. If your organization uses GPO, rules may need to be created centrally by IT.
4. Check for third-party endpoint security controls.
   Some security suites block multicast or UDP broadcast traffic by default. If rules cannot be changed, consult IT.

If you need port-level requirements for IT, use the related port reference article.

Related articles

• Network ports and protocols for WinDiscovery and Masterclock applications