Loopback adapter won't link on M4100-D12G ports

In the process of assisting a relative troubleshoot a new home Internet router, I was recording a video to demonstrate how to test a switch port with a loopback adapter. In the process, I discovered that I couldn't get a linked status on a M4100-D12G switch.

This port provides a connection for other network devices including a laptop and cameras.


I tried both a RJ45 and Gigabit loopback adapter and well as one I'd created myself.


All these loopback adapter work on a Netgear 5-port switch and a home router with integrated switches.


Is there an explaination of this behavior?

Model: GSM5212|M4100-D12G|ProSafe 12 ports gigabit fully managed L2 switch
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Re: Loopback adapter won't link on M4100-D12G ports

Check the switch logs ... STP will disable the port quicker than the link LED is coming on.

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