Very interesting discussion. Thanks Guys.
Obviously, better quality ethernet cables will work better, even just in 'normal' use.
Cheap eBay cables are a nightmare, thrown loads away that have caused all sorts of odd problems over the years in the day job.
So tend to make my own now with some quality cable and RJ45s. and keep those contacts clean to reduce packet loss as they will tarnish....
I already use fibre on the backbone links (trying to reduce RF noise!) that made a difference to the network in general with smoother transfers (all 1Gb/s) compared Gb copper, you could goto LAG 2x SPF if you wanted... (I've done that on the server.) and of course the most important part of this all is a nice fast layer two switch. That's where my money went and boy was it worth it.
MarkA