On connecting BroadBand WAN interface to a switch causes the port to go down. Only after restarting the switch port is OK when connected a laptop.
But still Connecting BroadBand WAN interface causes port down.
What could be the issue.
Switch - Cisco 4507
BroadBand - REDLINE
REDLINE Vendor complains switch issue.
On the same port I connected laptop and no issue.