@georgejhunt can you explain why the captive-portal service fails immediately upon "systemctl start captive-portal" (and during boot) on these 2 RPi 3's?
10.8.0.18
10.8.0.22
And yet the service starts (on boot, or manually starting it as above) on these 2 RPi 3:
10.8.0.42
10.8.0.46
Is this in way related to analagous issue (#1321) on Ubuntu?
Ref: PR #1300