They have different categories for restricted regions which you can find
here but if you will ask them they will say not to use it but the main concern I was having was Gamblers from restricted region who use to bypass it when it's illegal in their country whether their intentions are good or bad the casino will have to comply with the rules.
VPN is always a discussion and question is it allowed or not? I always use a VPN every time I access Duelbits and so far I haven't had any problems, but for other casinos I always use a mirror site, so it's highly recommended that Duelbits also have a mirror site so that users who can't access it because it's blocked by the Internet Service Provider can access it through a mirror site without using a VPN, and users who play using a VPN are not bad people more concerned about privacy, but if you want to use a VPN it is highly recommended to use a paid VPN not a free VPN because free VPN is often an obstacle either because it makes our connection slow down a bit and so on.