SUMMARY networkcheck.kde.org has HSTS enabled, so if you ever visit it with HTTPS, your browser will only try to load it with HTTPS, which breaks captive portals. STEPS TO REPRODUCE 1. Visit https://networkcheck.kde.org. 2. Join a captive portaled wifi network (coffeeshop, etc.). OBSERVED RESULT https://networkcheck.kde.org has a certificate error. EXPECTED RESULT http://networkcheck.kde.org gets redirected by the captive portal to its own login page. SOFTWARE/OS VERSIONS Linux/KDE Plasma: Fedora Linux 40 KDE Plasma Version: 6.1.4 KDE Frameworks Version: 6.5.0 Qt Version: 6.7.2 ADDITIONAL INFORMATION This should be an easy fix – just turn off HSTS on networkcheck.kde.org. (This won't help people who've already visited it with HTTPS, but eventually the HSTS will expire and they'll be fine.) You can tell HSTS is enabled by running `curl -v http://networkcheck.kde.org` and looking for the Strict-Transport-Security header.
Thanks for advising - this was due to an configuration oversight and wasn't intended - we actually had configuration to remove this but it had no effect due to the wrong set of header tables being changed. That has now been corrected.
Oh perfect, thanks!