Yes I also think this casino is one of the best vpn users friendly Although I don't know when or how long it will last . And yes most of the case when some players use free vpn which are not provide the best service then they face some errors. Even then it's quite vpn friendly but it can't speed up internet speed so I also think it will be a good step if build miror link taken .
They don't allow use of VPN if you are playing from a restricted region so we can't say they are VPN friendly casino and you can read it in their T&C in which they clearly mentions about it
https://duelbits.com/tosSo you are using it on the risk and once they find about it you know the consequences of being banned.
When it comes to a centralized service in which we deposit our money, like a casino or an exchange, it is better to not use a VPN, I have always thought that this is the best because even if it was explicit stated that a VPN is allowed, a change on their TOS could happen at any time.
And since most people do not read the TOS or at best they just do it when they open an account then you may find yourself violating a rule you did not knew that it existed, so it is better to stay on the safe side and avoid using a VPN while using services like that.