Video does not play in the browser Content type: video/mp4. What else to try?

Question

Browsers

1. There is a fresh Windows 10 Pro N (installed a week ago)
It has the latest versions of Vivaldi, Opera, FireFox and Edge browsers installed.

2. None of these browsers play HTML5 video on sites if it is in video/mp4 format. (no sound, no video, as if the file is not available)
In WebM and Ogv formats - it plays fine (checked here: https://tekeye.uk/html/html5-video-test-page).
In particular, not a single video on the Vimeo website is played.
Local MP4 video files open without problems (using VLC and MPC, but browsers also do not play them)

3. What I did:
+ Updated video drivers (Intel HD Graphics)
+ Installed a fresh K-lite Codec Pack with reset all settings
+ Installed Adobe Flash Player
+ Disabled hardware acceleration of rendering pages in the browser
+ Installed the h264ify add-on
+ There is nothing significant in the Windows logs, only the rasman service cannot start from errors

4. What else to try, where to look?