Thanks for the link.
Perhaps it works when I set up my own router because I set it to use Google DNS, whereas the SH3 doesn't have any custom DNS settings.
Or it's the persistent PUMA chipset stuff that is plauging their equipment...
I've had to take my own router off as it is old and doesn't have 802.11AC, but as soon as I set the SH3 to Router mode, Netflix stopped working again!
Going to have to spend some time ringing them up, I guess!