I wouldn’t say he admitted it either. I’d say he’s bragging about it.

That does not sound dumb at all. In fact it reminds me that that was the solution to a similar issue I had in the early '90s trying to make an IBM7171 (RS233 terminal attachment unit) work in a different building. I’ll give it a go!

The Cisco switch says all pairs are open - which is clearly wrong as it’s working at 100Mbit/s. That’s why I asked about a ‘proper’ termination to get a more meaningful result.

It’s cable spec’d for direct burial and it is direct buried. Damage during the trench backfill is the most obvious answer - I’m just making sure I’ve covered all options before abandoning it.