This sounds like the solution the provider offered when they commercialised my student internet connection. A building with over 1k connections had 4 ipv4 adres

This sounds like the solution the provider offered when they commercialised my student internet connection. A building with over 1k connections had 4 ipv4 adresses and no proper cgnat. This means you get niceties like: * Everyone gets their neighbors favourite language in the search engine if you have a incognito session. * Only about 32k sessions possible per adres. And yes you can claim them all and kill everyone's internet connection. * All local ip's were interconnected and not firewalled. That was fun. * You get banned or soft throttled everywhere due to "strange behaviour". They were doing it on the cheap and fortunately got told it would void their contract if they did not provide something better and it was "fixed" after about a year. But during rush you would still end up maxing the 4gbit fiber uplink even with only a fast ethernet connection for everyone.