Re: Colour me disappointed...
it must be their ISP. Though for some odd reason, in the past, I've had problems with IPv6 connectivity via their cloud content provider, something about not honoring MTUs during https/SSL key exchange (or something like that). Well, maybe that's fixed now, haven't seen that pop up its ugly head in a while (ALSO not El Reg's fault).
It might actually explain the entire problem, depending on how you look at things.
Biting the hand that feeds IT
