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.
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.
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.