Ian is such a untrustworthy prick, you can never trust that guy,

I've had switches, well, two switches, lose individual ports. One then went on to fail completely. The other stayed working on the other ports until I replaced it.  In both cases there was no warning, it just happened. I'd suspect whichever switch you're plugged into.

IIRC they were both cheapish Netgear things, little white boxes, 5 port. Can't remember if they were both gigabit, but the second one was. I have a better 16 port Zyxel thing now with everything for the house going through it, except the wifi which has access points connected to the main router which hangs off the fibre ONT on the wall.

Could be Ian though. He's known to doze off.

I've had several small, cheap switches fail. I was going to try different ports when it started working.