UNET Authoritative server how much reliable?

I am making one multiplayer card based game where 6 players can play the game in same room. so for decision making, I want to develop authoritative server. Unity networking provides high level API for developing Server side logic and the same machine can also be client. so is that reliable? How do I use UNET so that server logic will be deployed to the dedicated server like Photon allows and all clients joins to that server only? all decisions should be taken over that dedicated server only. Is there any way to achieve this via UNET or should I go with photon server?

Please let me know if you didn't get my question. Thanks in advance.