How many PS+ subscriptions do we need to play on a private server over the Internet?

Question

I want to play Ark: Survival Evolved with a friend. We both got a PS4, but no PS+ subscription (yet). I've read that you can host a non-dedicated server on one of the consoles or get a 3rd one and host a dedicated server there. But I'm unsure of how many PS+ subscription are required, if any at all. I've looked on the web, but found contradicting information from several years ago. Now I'm even more confused than before.

Do you need a PS+ subscription, when hosting and playing on a private server? If so, how many PS+ subscriptions do you need (e.g. 1 for the dedicated server + 1 for each player)?

Answer 1

According to this help page:

In almost all cases, a PlayStation Plus subscription is needed to play online multiplayer on the PS4™.

This seems to be the case for Ark: Survival Evolved, since the game case (for physical copy) and page in the store page say:

Online multiplayer (2-70 players). A paid-for PlayStation Plus membership is required.

So you need one PS+ account per console.