It is possible that your ISP's DNS cache has not ben refreshed in a while? I have a slightly similar problem - there is one forum that I can access from anywhere except from my hotel in Ottawa. It does not make a difference which computer or phone I use, I cannot go to that one site from there. Anywhere else, I can access the forum from the same laptop or phone.

The problem is that the hotel's ISP has not refreshed their DNS cache and refuse to accept my opinion that such is the case.

Cheers