WinDiscovery is blocked by Windows Firewall or endpoint security

• 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

• 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

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. Temporarily disable Windows Firewall for a quick test (if permitted).
   If discovery works when the firewall is disabled, create allow rules rather than leaving the firewall off.
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.

• Devices are discovered consistently on the affected PC
• Discovery remains stable after reboot and after restarting WinDiscovery