Android loves to auto-disconnect you from any Wifi network that doesn't provide Internet. You need to go through a bunch of arcane settings to disable that feature.

Settings, Network and Internet, Adaptive Connectivity - if anyone’s looking for it.

Thanks a ton. Now I know why connection to my camera's wifi access point drops on my Android and what to do about it. Thanks a ton!

Also a thing to consider for some digital audio mixers. Many can broadcast an AP for use with a tablet/pc for app-control. No way in hell I'm connecting my mixer to the internet during a show! The last thing I need is some script kiddy DDoS'ing the mixer and crashing my console.

You can spoof internet by responding to http gets on any IP. Last I checked phones didn’t require a valid https certificate as part of their portal detection.

This was my thought as well. I think the workaround is to have the device present itself as a captive portal type of thing, like you might encounter at a Starbucks, so that when the user is prompted to "Sign In" they immediately find the dead drop.

However I haven't actually played with this and don't know if that would work, or if the network would require DNS to function properly.

That's exactly what this project attempts to do. It acts as a captive portal.

Oh, excellent. I didn't catch that in the portions I skimmed.

Wifi Pineapples have a lot of codebase which can be used / reworked to do something like this, throwing up a captive portal on a web server.