So finally got the right version of the Apple Service Diagnostics and burned it to a CD. Boots up. (Non-Apple keyboard/mouse hooked up through a USB hub worked when I held down on the C key.) Ran the Ethernet test. Everything passes. Ran the entire test set three times. Everything passes. But still no Ethernet. Cable last tried was pulled from a working port on an Intel Mini. The Intel Mini connects via 100 base-T connected through my ancient hub. Same setup does not work for the Mini. The extensions, as I remember them, are installed. Something is wrong with the port that is beyond the ability of the hardware test to determine.
Anyone have any other ideas?
OK, went and bought another Mac mini G4 off of eBay, listed as starts up, but HD untested. Got it today, it booted up into MacOS 10.5 once I hooked it up. It had an IP address. Shut it down, took it apart, removed the HD, took apart the Mini with the non-working Ethernet, got the SSD out of that one and put it in the new one. It's currently running with full Ethernet access and can access my SAN. Definite improvement.
But, the other issue with these...Sound. I have a sound device plugged into USB, Apple Profiler recognizes that it's an HID (USB Audio Device), but it's not selectable in the Sound Control Panel. USB Overdrive doesn't have any options for it either. How do I get this to work for sound?
This is the one I ended up getting to try out.
https://www.amazon.com/gp/product/B097H7HB5J/?th=1