Network tone generator freezes when connected to one particular ethernet port?

Network tone generator freezes when plugged into a particular ethernet port.

I use a Trendnet tone generator like below:

It generally works extremely well. But yesterday I plugged it into an ethernet port and the LED lights on it appeared to have faded. I plugged it back out again and immediately all the LED lights illuminated again.  Obviously, I could not complete the network probe test because in this state it was obviously not emitting a "tone". What happened here? I've never seen it do this before.

(BTW, Looking at the front of this device it says "not to be used on live circuits")
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JohnBusiness Consultant (Owner)Commented:
Are you using the upgraded device?  One on the two shown has been discontinued.

Verifies cable continuity, opens, shorts, and miswires   <-- It would have difficulty doing this in a powered circuit. Is the port a POE port?   That would be in line with the warning on the front of the device.
furunoAuthor Commented:
John, there is no evidence of a PoE injector on the network.

BTW, using NT2 version
JohnBusiness Consultant (Owner)Commented:
Interesting. Ports that are plain should all work the same way. I will do some looking
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Andy BartkiewiczNetwork AnalystCommented:
Sounds like the port had an active data or phone connection. Most toners will not work on those, but it usually tells you why its not working
Are you testing from the device port or switch / patch panel?
The NT2 isn't a tone generator it's a cable continuity tester.. There's a difference

You should be using a tone generator with wand to trace the connection points, unplug from both ends then test the cable with your NT2

Personally I'd recommend AT8LK (at a minimum) it also has the ability to flash switch ports making identification a little easier
furunoAuthor Commented:
I'm testing form the ethernet port

The NT2 came bundled with a "wand" which is the receiving end. The two devices work in conjunction with each other.
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