Do this for all computers.

Install wine and winetricks if you don't have it installed already.
Homebrew is an easy way to do this. Install brew then,
brew install wine
brew install winetricks

Configure IPXWrapper in wine
wine ~/.wine/drive_c/GOG\ Games/Warcraft\ II\ BNE/ipxconfig.exe

Set Primary interface to en1
(if you launch Warcraft II and try to create a multiplayer IPX game, check ipxwrapper.log in the Warcraft II directory in the command above. Whatever Interface has your IP address, set your Primary Interface to that)
Set Network adapters to the same as above
Check Enable interface
Set Network number to 00:00:00:01
Node number will be auto populated – leave it
Check Enable Windows 95 SO_BROADCAST bug
Check Automatically create Windows Firewall exceptions

Play!

Took me a bit of googling and experimenting to get this working and thought I'd share it with everyone else.

For linux it works too but you must add wsock32.dll to winecfg dll library for Warcraft II BNE.exe