Error “LAN Port disconnected. Please connect LAN port to discover again.” in UCM’s Zero Config


Zero Config that is unable to auto-detect different subnets. Error “LAN port is disconnected. Please connect LAN port to discover again” pops up each time running the scan

Scenario or System Info
System Info: UCM6510
IP Range: UCM IP: GAC2500:

Troubleshooting steps
– UCM62XX is able to ping GAC2500

– GAC2500 is able to access UCM62XX.

– Manual registration works-

– Verify Fortinet has all ports open

  • Verify UCM’s LAN port is connected

– Verify there is no NAT configured in the phones or extensions.


a. Make sure that the UCM is in Switch Mode under Network Setting

b. Connect the cable to WAN port

c. Power up the UCM using PSU

d. Auto discover works

Cause : 
This is a known issue in UCM62XX and UCM6510. Unlike UCM63XX, in UCM62XX/6510’s WAN and LAN ports are identified. When you plug in a cable to UCM62XX’s LAN port and it discovers external devices (from different subnets), UCM will detect them via WAN port, so causing the error. 

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