Strange behaviour (bug?) on WS-12-250-DC

[createcoms]

Right now I'm looking at a WS-12-250-DC which has a Ubiquiti 5AC GEN2 PRISM connected on Port 1. In the past hour or two, this port started flapping (was solid gigabit before the event) between no link and 100Mbps. Cable testing fine.

What is *very* strange is that I've now turned PoE off and yet the port is *still* showing as flapping, which is impossible because if PoE has been turned off then the radio is off and cannot be establishing a 100Mbps link (or any kind of link)intermittently.

Running 1.5.4 firmware. Happy to downgrade to 1.5.2 if this is useful ?

Any other checks to help understand the fault here ?

[createcoms]

Device stabilised back to gigabit, appears to be fully functioning despite PoE being turned off.

[sirhc]

If the switch is damaged the 24V MOSFET can be fused ON meaning it will always be powering 24V even if turned off.

You can check this by going on site and plugging in a 24V device into that port with a short cable with POE OFF and see if the device powers up.

Now if your link is dropping and flapping with POE on I would suggest bad connection or dirt in connector or lose connection.

[createcoms]

Thank you for the prompt response, I suspect we are indeed dealing with the fused mosfet. Will proceed with replacement and checking of cabling/radio.