Chris, I have to wonder if Support has even read this thread, considering J has posted his traceroute results which contains the address they're looking for. This really is starting to remind me of my prior ISP, who's frontline staff were both not capable as well as not being allowed to deviate from the help script which was adamant that the problem was always in the customer's location (I need to stop, or I'll be diving into the bourbon before 10:00 AM.)
The first line of the response also has me scratching my head. tvwbb.com shouldn't be able to tell (shouldn't care at all) if the client is on a WiFi, wired, or 2 cans with string connection. "Blocked by the server"? While it may be advantageous to run a firewall configuration on tvwbb.com, you [hopefully] should be running a minimal configuration, only an HTTP server and maybe an ssh server (on a non-default port.) I'd also suggest that a discussion of a firewall configuration not happen on a publicly visible forum.
Was that their entire response? Any idea why traceroute would fail from my end, yet the site runs fine for me? Nothing about the [misconfigured] reverse lookup?
I don't disagree for a second that the problem absolutely isn't at the client end for J. There is definitely something strange going on, and I am wondering about ssd19-ga.privatesystems.net (or their edge policies as a whole,) being the last hop before tvwbb.com.