@jwlv
Your comment above (>>> "If it is on, when you connect to the Echo's Wifi (amazon-xxx), your phone will automatically switch to cell data because there's no internet access on amazon-xxx." ) made sense and sounded logical when I first read it, but after further thought about it does not seem to be the case for these reasons:
1) I have setup many Echo devices with that feature always ON on my iPhone, and Most every device got set up, if not the first time, then after another try or two.
2) I have a few different wireless drives; both hard drives and flash drives, and of course, there is no internet on them, only their internal wi-fi signal. I have media on these drives I can access for a long time (e.g. a movie) and I just stay connected to drive's wi-fi (but cannot use my cell phone or internet). So, obviously my phone does not auto-switch over to cellular network just because I have no internet. I see no difference between amazon-xxx or a wireless drive's signal in this regard.
Am I understanding this correctly? If not, tell where I am incorrect.
(As an unrelated-to-Echo side note regarding the wireless drives:
They have a feature where they can be connected to internet if I concurrently connect the wireless drive's wi-fi signal to the home network's wi-fi, then I have other capabilities such as internet access so text msgs, etc can come in, and I have flexibility of moving away from the wireless drive and going anywhere with my mobile device my home network wi-fi signal is strong enough, and I do; to watch movies on iPad, etc.)