[Solved - see comments]

Hi, just put LOS 15.1 on a new phone (mix2/chiron) and having some troubles with WiFi.

On my previous phone (running cyanogen), a quick settings put global captive_portal_server g.cn had it sorted nicely, but this seems to have no effect on LOS 15.1 - it still says 'Connected, no internet' despite everything that's not blocked here (china mainland) working just fine.

Some googling suggested that LOS 15.1 might prefer settings put global captive_portal_http_url http://g.cn/generate_204 and settings put global captive_portal_https_url https://g.cn/generate_204 might help, but to no avail.

So, what specifically is the setting that controls the captive portal detection URL in LOS 15.1, since everything I've tried and googled so far has no effect?