Having some issues in Plymouth, I'm in the PL6 area.
I've only lived in this area for a month or so, performance does vary.
I managed to change my upstream channel yesterday evening, as I wasn't able to stream anything through the ROKU...
You can clearly see where the upstream change happened, although it improved things, I was only achieving about a 30Mb download speed on a 100Mb connection. Streaming and web-surfing however worked fine...