This is likely a minor bug in the original firmware 2.1.7 — in that firmware, the WiFi setup requires the browser to send acknowledgement, but some of the newer phones, like my pixel 2, would disconnect the WiFi as soon as the controller switches to station mode, causing the controller to never receive browser acknowledgement hence can’t finish the setup. The newer firmware, 2.1.8, addressed this issue by not requiring browser acknowledgement.