@Clive_A cable degradation definitely could be happening. It was the best wiring (CAT5E) I could install in the walls over 20 years ago. It's been able to support gigabit 1000Mbs for about a decade...

I recently upraded the firmware on my TL-SG108E V6 gigabit switch to TL-SG108E(UN)_V6_1.0.0 Build 20230218. Prior to that, it was on Build 2022xxxx. While I was on the previous build, one of my ports...