Possible reason why you can't access the page is that your country is restricted due to Casino license.
What I suggest is to try to open
www.twicedice.com with VPN enabled: this often solves the issue 👍
Does it mean using VPN to play in your casino is allowed? Or it's just solve the access to visit your casino only? I didn't find any rules on your ToS about using VPN. Because a case like withdrawal blocked due to VPN is nothing new on other casino.