So... Interesting Developments in this stream of consciousness testing documentation:
As I mentioned above, I had dropped my Dash back to Factory settings, and then upgraded to 1526 firmware.
I left my Dash unplugged this weekend, and when I powered up it asked for an identifying SECURITY QUESTION before continuing to connect to the network.
(note: asking that question is what it did NOT do previously)
This time, it connected to the network, but then failed as it could not download the Control Panel (... no surprise there).
I powered off, slapped in the Chumby software on USB, and proceeded
Still, I could not connect to my main home SSID, but I could (as jhonryan suggested) connect to my phone hotspot.
Surprisingly, while I expected the Chumdash info to appear, it loaded the default 1526 dashboard. weird.
Reboot with the USB still back in.
This time, I'm prompted to install Chumby, and up pops the Chumdash 1.0 skin. OK... nice.
USB out, Power off & Reboot - connecting to the hotspot: Booted up, displayed expected dashboard, no problem.
Power off, turn off phone hotspot, power up: Starting Chumby, checking network, Create a new connection, scanning, Select main home SSID, enter (after validating) passphrase, allow DHCP...
Network connection failed...
wlan0 link is down
failed to obtain IP Address
internet is unreachable
So, that's weird.
Every other wireless device in my home (and there are MANY!!!) connect to my Linksys EA8500 router without any challenge.
I checked the router, and validated there the SSID, Password, and it's security is WPA2 Personal. That is the 2.4 Ghz band (the 5 Ghz band uses a different SSID). My DHCP server is enabled, there are plenty of addresses (but just in case I increased my maximum users from 50 to 75)
Rebooted to see if the 75 user limit would make a difference...
So, before jumping to the conclusion of: "Well, it's yer router..." keep in mind that this thing connects to printers, wireless bridges, other computing and IoT devices...
NOTE: I have WPA2 Personal as my security level, while the Dash thinks that Security is AES. Could that be it?
Wait minute... I just rebooted, and this stupid thing just connected! (no, I didn't change security) What the hell ??!!??
SOMOFAB%TCH..... Looking at the Wi-Fi settings, I have the 2.4 Ghz setting as "802.11N ONLY"... because I did not want slower mixed devices to connect. And the stupid Dash supports 802.11B and 802.11G... but it is well pre-802.11N
OK, it's not the router. It's the user.
Change the router to "Mixed" for wireless.
Unplug, reboot, Slow, but Chumdash loaded, and it did not prompt me for network connection info.
Now the next question is will the 802.11B/G connectivity slow my overall wireless speed from 802.11 N to the slower B/G/N Mixed settings. But that is for me to resolve.