And I just solved my own problem. . . . I don't know why though.

All the connections tested good outside of the game. The older I5 computer is using a USB network card.

I moved the USB network card from the front USB 3.0 port, to a rear USB 3.0 port.

Making that change solved the issue. My ping ...

I have a older I5-3470 computer and a newer Ryzen 5 3600 computer.

Both computers can run massive complex factories without any issues when in single player. Both computers are rock steady at FPS/UPS = 60/60 when in single player

LAN multiplayer is currently not possible no matter which computer ...