Plutonium

StevieS2P You're trying to host the private match the wrong way. Check my response to OP and/or consult the official guide for hosting custom games on the plutonium launcher website.

legendlcgames Oh you're trying to host the match the wrong way. You don't host private matches with "Host online" in the "Cooperative" section of the game, you host them in the "Solo" section. I know its confusing and even the official doc on it can be a little confusing. Essentially you select "solo" and then choose what mission you want (scroll down for zombies), then enter the command to set the min players for the game to start (that way the game doesn't start before everyone can join). Then launch the "solo" mission (its not actually solo) and your friends can join you after you load in. Once everyone's there the game should start itself but if it doesn't there's a command to force start it. I don't have permissions to post the link to the official guide but its on the plutonium website (where you downloaded the launcher) under "support" and then "custom games/playing with friends".

Resxt i guess the only real advantage I can see is to have all my profiles connected in the same place. Is there any particular client you would recommend? i would trust the plutonium team with my banking account number but I'm antsy about any other names cause i'm unfamiliar with any of the other 3rd party client developers.

There was Xlabs but it got shut down. No idea if the Plutonium Devs have any plans to add support for mw2 but they honestly should since its the last of the golden era cod's (cod4 has an official remaster so it doesn't count)