There is no effect even when I connect an Android 8.1 phone to IIAB 6.7/master with a verified-running captive-portal service (except possibly many minutes later, when Android 8.1 started hounding me "Sign in to network" ? Which certainly didn't do much anything at all...)

Caveat #1322 this new captive-portal service runs on 50% of my RPi 3's but not on 50% of the others.

Caveat #1321 sadly this new captive-portal service appears not to run at all across all Ubuntu IIAB's so far.

While I'd very much LIKE to test Android 8.1 against IIAB 6.7/master on Ubuntu, so far the result there is even worse (Android 8.1 hangs forever with "Obtaining IP address..." — possibly related to/exacerbated by dnsmasq failing to start on that machine #1320 ?)

Ref: PR #1300