Is this the same as when you try to visit some site but doesn’t work unless when you visit with a vpn or change the network provider.
I have experienced it in several sites but never have I tried it in any casino before since I don’t want to use vpn and out my account at risk, even sometimes I’m unable to visit or open sites like Reddit and quora but google search works very fast and when I change the network provider or turn on vpn everything becomes normal.
Is this what you’re referring to?
It is worth noting that some gambling sites specify in the terms and conditions whether a user can use a VPN to access the site or not. In addition, some casinos may display a pop-up window during authorization if a VPN is not allowed. In this case, you're not putting your account at risk.
As for the sites that you described, it sounds like a temporary blocking by the ISP. For example, in my case, the ISP, as a rule, blocks access to gambling and other sites by resetting the connection or, as I wrote above, strongly slowing down the connection speed to a particular site.