Hi Dave,
I’ve just caught up with this thread. Can I ask you a couple of questions. When you set the dead slug up did you assign it a static IP or did you set it up to use dhcp? If dhcp which router are you using?
The symptoms you’re seeing are reminiscent of a ‘bricking’ I had a few months ago that was cause by a nasty (and rare) interaction between my router firmware and the slug dhcp network stack.
Thanks,
Rich