Gonna try to make the situation concise with bullet points to be concise. I don't mean to be rude.

1. I am trying to play WaW Campaign Co-Op with my girlfriend.
2. We have both purchased the game on Steam.
3. I bought my game before the keys ran out. We bought her copy recently.
4. We both have our games and PW launchers up to date.
5. We both have PW accounts (and follow eachother).
6. We only made her account recently.
7. She is unable to host LAN via the game's native menu.
8. When I host LAN, she has connectivity issues, so I am attempting to run it with her hosting.
9. We live in the same house and are connecting to the same router.
10. We are unable to play with native LAN (instead of PW) because of the whole Online Account thing. I don't get it, either.
11. I have attempted to host an online match on her computer. It results in "Your authentication ticket could not be verified because the server you are trying to connect to is not authenticated to Plutonium."
12. I have attempted to start a solo match with "sp_minplayers 0" on her end. Same prompt.
13. I typically attempt to connect with local IP address instead of public IP address.
14. Connecting with public IP address creates "Failed to log on." on the cmd.

What do you guys suggest?

Thank you.

My wife approached me, telling me that she wanted to play a shooter with me. She's played some games with me, but wanted to try a CoD game. I thought the best way to get her into this was by playing some WaW co-op, taking her through the Campaign with me at her side.

I bought her WaW on Steam. She downloaded the game. The online profile bug happened, not even letting us play LAN. We refunded the game. She kept the files downloaded. We downloaded the Plutonium launcher. We used those game files as the files that Plutonium would run the game off of. I bought WaW on Steam years ago, so my copy is golden.

We both booted up Plutonium. I made a Private Match, used the "xpartygo" command, and she tried to join me through the Friends list after my game had loaded. A couple seconds would pass, her screen would say that the server disconnected. My screen would say that she timed out.

We tried this multiple times, changing certain ingredients in our recipe for failure.
For example...

I tried starting the match through Solo instead of Private Match. No dice.

She connected with console (connecting to my ipv4). No dice.

She hosted the match. No dice.

We went on 'seperate' internet connections (2.4ghz and 5ghz). No dice.

Tried connecting while loading the match. Tried connecting while paused. Tried connecting while match was active. All fruitless efforts.

Around this time she memorized the You think because you say nothing, you are strong? speech that the Japanese officer gives in the beginning. She is now indifferent to Pvt. Pyle getting his throat slit.

We made sure that all the settings were right: we were on the same private internet connection, her computer could run the game just fine by herself, the network was set to Private, I had even port forwarded in the hopes that would do something.

I had a whole convo with some guy on the Pluto Discord in the hopes that he could help me with my problem, but he couldn't help, and we ended up agreeing that coming here would be the wisest choice.

As it stands now, we can't play together. I'm just going to buy her MW3 and play co-op with her there. A shame Plutonium doesn't MW3 co-op available.

If you can help, please do. Thank you.

Other things of note:
She's on a gaming laptop, GTX 1060 M.
Neither of us have anything beyond Windows Defender. She doesn't use her PC often and I know my way around the internet.
Ports are still forwarded.
I have the Pluto launcher added as a non-Steam game to Steam, and usually run it through there on both computers. This isn't the problem, because I tried everything again without using Steam at all.
No custom maps are installed.
A zombies match fails to connect, too.