If I remember correctly, UDP on 127.0.0.1 did work fine on my Win7 development rig, but not on my XP64 rig in the cab.
She seems to be saying it should be fine for Win7 and up, but not on XP? I haven't even tried to run this yet, so i'm not saying i have any experience.
In later posts she talks about changing from 127.0.0.1 to the local actual ip so that definitely seemed to fix part of the issue as it wouldn’t get past the black initial screen until I changed that. It fixed everything after that except for one pc flickering.
I tried using gpt4 to see if something is wrong with those latest settings but it was not super helpful. It suggested changing the pc that is master which is a good idea. Right now I can get both pc 2 and pc3 to each separately flicker in a 2 player race (using 3 linked cabs though). So I expect the pc 1 to flicker once I make it a slave in the set. It is just odd that I am pretty sure I had all three working with no flicker at one point before it came back again. Not sure if the issue is sporadic or if I just missed the flicker somehow.
SailorSat mentioned something about not starting the game with player 1 but I think that was referencing the 9th player preview if I recall and anyhow my player 1 auto starts and inserts a coin every time automatically whereas player 2 and 3 (after an initial race) allow me to insert or not insert a coin to start or not start those. I also wonder if an odd number of players (3 players in my case) is supported with m2lagfix.