I would presume there could be an issue between the 835 and the ISP modem. Those modems with built in routers, even though there seems to be a bridge, could be possible that there is something going on. I had my 835 online about 2 weeks ago for test. Speeds were expected for my ISP and the 835 is on same FW version. However my ISP Modem is a stand alone modem, no bridge or router built in. You might want to ask Shaw if you can use or if they have a modem only option.
I would test the 835 at your friends place to see if the problem follows. Unless he has same ISP modem? Still worth a test.
Keep us posted on how it works for you.
Good Luck.