The HTML client only listens on a single port, so it cannot be installed on the standard 80/443 port pair that is used for HTTP(S). This would be very useful as it would make it much easier for users to enter the URL for their site.
It actually works well on most browsers if you start web access on port 443. They will automatically switch over to port 443 when they fail to connect on port 80.
Except Safari, for some reason. On both iOS and macOS, you just get an error and have to manually add "https://" to the URL.
The issue seen on Safari has also been encountered in Edge on both Windows 10, Windows 11 and macOS 12.
No issues in Google Chrome, however.