I want to use a vps/dedicated server for game hosting. I expect hosting a lot of servers on that. For the connection, should I assign a unique port for every server or change IPs for every server. And how would these 2 options impact on the game, if I had multiple vps/dedicated servers.
Performance-wise, it doesn't matter. But IPv4 IP addresses are a rare commodity, so you won't get more than one per server unless you pay extra. Not so with IPv6 IP addresses, though.
But if you are the game developer, then why run multiple processes of your gameserver instead of just writing your gameserver in a way that it can handle multiple game session at once by implementing game sessions on the application layer of your network protocol?
If you go the route of multiple servers per machine then you can have you're server bind on 0.0.0.0 & then have each new instance of a server increment a port from your set base by +100. Server 1: 0.0.0.0:7777 Server 2: 0.0.0.0:7877 Server 3: 0.0.0.0:7977 ...