Could you recommend a suitable game development engine for creating peer-to-peer multiplayer games?

I’ve always wanted to make online multiplayer games, but the idea of paying for servers held me back. I heard about peer-to-peer as a way around that, but it’s a big topic, and I don’t know where to start.

I know about systems like Photon and Mirror for online games in Unity. If I want to do peer-to-peer in Unity, what do I need to know? Where should I start? Are there tools you recommend, and are there things I should be careful about?

I’m new to networking and online stuff, so do you have any easy-to-understand links or resources to help me get started?