@camel288  I'm facing the same issue.

The "Unmanaged Pro Configuration Utility" sees three of my four switches. One is a TL-SG1024DE, three are TL-SG108E.

One TL-SG108E is not recognized at all, and it is also the only one with all leds switched off despite properly functioning. Power cycling did not help.

The switches are about same age, i.e. MAC addresses are only different in last byte.
The other two I provided a firmware upgrade since they had (I think) 2014-05 firmware.

Any ideas?

Thanks.

@Sjoske 

If the port LED off, maybe the switch is already broken. You can use a cable to connect two switch ports directly, for checking whether the port LED lights.

If the port LED is normal, try to change the utility version.