Re: Roku F-u
I'm not so sure the issue is "fixable".
This would imply the Roku has _2_ radios, and not just the single radio I've been able to find so far.
The single radio it has is a dual-band (but not simultaneously both bands at the same time) 2.4 and 5GHz. You'd need an entirely separate radio to make your setting even possible in a wirelessly-connected Roku scenario.
Therefore, if you don't have the device plugged into a wired LAN, you are forcibly limited to being on the same channel that the Roku is already tuned to, to access your WLAN.
When plugged into wired Ethernet, you can rightfully expect it to honor your settings; when connected wirelessly it cannot.
If your Roku Streaming Stick for example doesn't have a Wired connection to begin with, you're SOL - or you could always leave it as an island, with no Internet connectivity, and expect it to perform admirably on your preset channel Wifi-Direct-only.
Biting the hand that feeds IT
