in your game folder, there should be a file: game.cfg.
make a copy of that file and place it in your My Documents folder. This will help get around win10 whining about privilege's and whatnot.
you can open the game.cfg in notepad and with the copy, you can make edits to that file.
open the game.cfg and scroll down until you see this:
// MULTIPLAYER
mpipaddressstring = "0.0.0.0"
mpgateserverlocalportmin = "45001"
mpgateserverlocalportmax = "45500"
mpgateserverlocalportdelta = "1"
mpgateserverlocalportrandom = "0"
mpnovaworldportmin = "45001"
mpnovaworldportmax = "45500"
mpnovaworldportdelta = "1"
mpnovaworldportrandom = "0"
mpnovaworldlanenumsessionportmin = "45001"
mpnovaworldlanenumsessionportmax = "45500"
mpnovaworldlanenumsessionportdelta = "1"
mplanserverportmin = "45001"
mplanserverportmax = "45500"
mplanserverportdelta = "1"
mplanclientportmin = "45001"
mplanclientportmax = "45500"
mplanclientportdelta = "1"
mplanclientportrandom = "0"
mplanservertojoinportmin = "45001"
mplanservertojoinportmax = "45500"
i have had much more success in setting specific ranges in my hosting setups rather than just using the single ports for JO.
what you want to do is set the game.cfg port numbers to the same as the ones you set in your port forwarding setup. once you have made those changes, save the file and make sure to select "all files" in the dropdown and for added measure, find and double click the game.cfg to save. then after you save, copy the edited game.cfg and paste it into your jo directory. select replace file in destination when prompted. also, dont forget to double check any firewall you may have(including win defender firewall) to make sure they are allowing traffic through them for joint ops.
the ports above are for my play machine in the event that i decide to host from there, usually for a map test.
i hope this works for you as it has for several years for me.
