UCM 6204 Network unstable with WAN port



My UCM 6204
Route Mode

LAN Port.
VLAN TaG “2”

WAN Port
VLan is Disabled

Bothe Ports Connected to Same Managed Switch. Where the ISP is Connectes to Provide the Internet to the Network

ALL phones. Same VLan “2” and phones. Works fine and Get. IP Address from the UCM DHCP

The Problem is when I connect the WAN Port to the switch (Same Switch)to get Internet from ISP router . To Connect the UCM Remotely the UCM Become unstable and the Ping is reply for Seconds then Timeout.

I try to Set all Phones. Static IP. And i Have disabled the DHCP server on the UCM. But still Same problem

Do i need to Set anything in the Switch ?



that is well-known problem. UCM6200 series has same MAC addresses on both NICs (WAN and LAN). If you connect them to same switch, switch gets confused with same MAC address showing on different network segments.


Then i think i need to run Cable to the ISP router Directly as Gateway


it really depends on type of ISP device. If device if some ONT or ADSL modem you will still have problems. If it is real router, with routing interfaces not switch ports you should be fine.


Then which model Have MAC Address For Each Port
6304 or 6208 ?