[SOLVED] How change WiFi when headless with no Ethernet?

I made up a stream renderer with Volumio, an RPi3, and a HiFiBerry DAC+ Pro. A wonderful little product for the cost, easy to put together, and even automatic use of the WiFi dongle. THANK YOU!

I took it to a friend’s house to demonstrate, but I couldn’t log it onto his WiFi, because the unit is headless and he doesn’t have Ethernet, so there was no way to control it. A chicken-and-egg problem.

Could I have done it if I’d turned on the Volumio hotspot earlier, so I could reconfigure the WiFi at his house with a browser on a phone or tablet?

Yes, use the hotspot.

Thanks, that’s helpful & answers the question.