What the site should look like:

What the site looks like via my Dad's connection:

i.e. When accessed via my Dad's cable connection, none of the main content is retrieved.
I have tried the following:
- Different browsers, clearing cookies and cache
- Connecting directly to the modem, rather than going through the router
- Connecting to the site via https://
- Adding an X-Forwarded-For header to the http request
But the only ways I have been able to get the site to load are
- Connecting via a VPN
- Using a different internet connection (works via my 2degrees 3g connection)
I think he is using the correct DNS servers (203.97.78.43, 203.97.78.44)
Does anyone else on cable have this issue?
Could it be caused by TCL's transparent proxy, or is it more likely to be a problem with the website itself?