There are those casinos that are really restricting users if they're found in those countries that they're not supporting. OP isn't on that condition I guess but rather there's a problem upon his access to gamdom.
It's working on my end and OP has to try it again if it's still not working, he has to check his ISP and everything related to his internet connection. But if still no issue found there, he can contact gamdom and address his issue that he's not able to load the website.
Maybe OP can try access with casino gambling platform have restricting trough with change setting on chrome browser, change to be public DNS trough with security setting on chrome browser. I don't try but right now my country restricting access to Binance as exchange market, when I change DNS setting on my chrome browser looks working and available to access some site have restricting before like Binance, maybe could working for OP with several casino platform gambling site have been restricting in his country.
That tip of yours can be done by anyone who thinks they're restricted to any website. Having the DNS being changed will make them access it but what's next if the casino detects them eventually and he suddenly changes it back to the normal DNS.
He's seeing all the suggestions here and whichever the best tip he probably think, he'll take that and do it so that he can play to the casino that he wants but if he's able to do it with gamdom, much better.