I have my own VPN server on a remote server on VPS. On some websites, very unknown and small ones, I've faced up to a restriction stating "It's likely that you're behind VPN or proxy, you're not allowed to use our website".
I don't want to change my VPN provider, meaning I don't want to buy VPN from a third-party and I want to keep using VPN. Which is, again, my own VPN.
How do they determine that I'm behind VPN? Does "likely" mean that they know a range of IP addresses of my and most popular hosting providers and it just infers the fact that I have a certain IP address?