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.