I'm not really expecting help.
I'm about to give up on the damn box. I mostly got it to stream Netflix and I'm sick of their damn rip-off rates, so they're getting cancelled r.s.n.
If it's "upstream" it's in Comcast's stuff, not mine, and there's nothing I can do about that and b-t-w, all those sources stream just fine to the computer. Maybe you can explain that, but all I've gotten is "voodoo" from Roku's tech support. I used to do tech support myself, and I can tell pretty well tell when someone's just running me through the routine boilerplate try-this-try-that.
Besides, if you read back through these forums, you see other people reporting the same problems. And nobody reporting any solutions.
Yes, I've changed the DNS settings to those Roku recommends and a couple of other public DNS servers.