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20 hours agoThe one use case is running STUN/TURN server for NAT hole punching, that requires two separate servers, or one server with two IP addresses. You will only need that to run masterserver for games that support hole punching, or to run VoIP telephony / teleconference server.
Another use case is reliability, when your server is connected to several network providers, it will keep working if one of them has an outage, and will naturally have a different IP address for each network link. But your VPS does not have several network links, otherwise they would advertize that in bold red letters.
Because you won’t determine the type of NAT during hole punching. This requires the client sending two UDP packets to two different IP addresses, then comparing their source addresses on the server.
Normally yes, you can just assume that two clients you are trying to connect both have port restricted cone NAT, and run the hole punching algorithm, and if the connection fails after ten seconds, show message to the users ‘Error 418: your router is a teapot’.