LED indicators on Ethernet cables

My patch p[anel is in a closet. Switches and network devices are elsewhere. To ease diagnostic while I'm in the closet, I would like to see if a network device is connected remotely. Half/full and speed would be helpful

OK, so you need the full functionality of an ethernet PHY including speed negociation. The PHY is the chip that handles the PHYsical layer of ethernet. For example optical and wired ethernet use the same protocol at MAC level and above, but different PHYs. Note the PHY controls the LEDs on the ethernet port.

That pretty much means you need a device with an ethernet port. It would be pointless to replicate that.

The simplest solution is to use any device that will work, like a laptop, a raspberry pi, or a USB-Ethernet dongle connected to the USB port of your mobile phone... and plug the ethernet cable, then watch the LEDs. Plus it has a screen and a GUI so you can even ping what's at the other end, or scan its IP address, so you know what device is at the other end of the cable.

Because patch panels are simply cheap connectors that just connect wires together. They would have to terminate a link from both devices with Ethernet chips to know what speeds they work at. Which is what an Ethernet switch already does.