So, I've noticed some inconsistencies with DirectPlay on Windows 10. For example, the 1997 game Outlaws, as long as you open the proper ports and both players have the same Windows OS and game exe, they connect fine. But yet, on the 1999 game Redline (the 1 I'm desperately trying to fix), connecting directly via IP does not work at all. I have tried numerous things, such as:

Enabling DirectPlay via legacy (of course). Both players using the same demo version. Both players using the same full patched version. Opening ports that the game calls for plus DirectPlay ports. Disabling the firewall on both the PC and router. Tried setting up a temporary DMZ on the router. Tried Kali but that didn't work (maybe ipxwrapper interfered with it, am not certain).

I know for a fact that connecting to someone else directly used to work, at least on older Windows. But I've tried 2 systems (Windows 10/Windows 10, and Windows 10/Windows 7) and fails each time, no games ever show up, regardless of who hosts or joins. (note: I have 2 different networks with different IPs, to simulate 2 people across the country connecting, I did indeed try IPX/LAN on the same network, and that works fine...and a Win10 friend across the globe tried direct connecting to my Win7 then my Win10 with no results...)

So my question actually is, has anyone had experience with getting DirectPlay to function properly for their favorite old PC game? Or, have you ever came across a similar problem? I'm just trying to look for some sort of insight, anything at all. Thanks!