The network technology was basic 10B2 ETHERNET on 50 ohm coax cables with strict rules on terminations and more. THAT hub has 10BT connections for other machines with a single 10B2 port which acted as a translator from 10BT to 10B2 networks.

These are not too rare in the used market but I rarely found them to die. What I did find was owners and networking admins that had forgotten how to wire and terminate 10B2 networks. Far be it for me to duplicate that here as today you can get that on the web.

I'd recheck my 10B2 network cables and terminations to see if something was undone.