My kids and their friends have lots of games that they want to play together.

If the game supports online multiplayer, they're fine.

But they sometimes seem to have networking issues, even if their friends are on Steam.

Is there some easy way, ignoring steam, for them to be playing as if they were on the same network, couch coop, sitting side by side?

I can do whatever is required on my sons computer - I can only do basic requests for his friends.

How can I make sure they can connect their PC games, no matter what?

PS: This seems to me the main difference between consoles and PCs, that and controller support