Me too, when I was still actively gambling at duelbits, I used VPN most of the time. I did not win big too, my biggest withdrawal from duelbits was around $3000 and there was no issue at all.
Ooo still a pretty good amount nevertheless. May I ask if you were using a dedicated IP or was it simply a regular paid VPN? I've never gambled in duelbits yet but I'm guessing they're VPN friendly?
If you gamble on a site through a paid vpn, that site will not understand that you are using a vpn, but if you gamble using locations in different countries at different times, then the site's cloudflare will understand the fact that your account is logged in from the IP of different countries at different times. I have used stake.com with free vpn and have used different country ips several times but I have not faced any problem. So I can say this site is also vpn friendly. This site is not accessible in my country so I can't access it without using vpn