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 .
I use VPN most of the times, but as far as I remember it all, I do not have any experience of having any errors while I'm connected to it and playing in Duelbits.
You'll have delay on your internet connection if you are using free VPN. Try using premium subscriptions from VPN services, it will increase your internet speed.