I'm using web interface version 1.2.8-10 , custom firmware version 3.03 (build 2368).
The VLC version 2.2.1 ActiveX plugin for Internet Explorer 11 on Windows 10 works OK when tested against Videolan's site using a MRL for a media file on my Humax HDR Fox T2.
The ActiveX plugin fails when launched from the Humax custom firmware web interface Browse Media 'Play' button.
(I'd like to show the actual HTTP addresses, but I'm a new member subject to spam prevention measures.)
The Internet Explorer F12 Developer option 'Console' tab shows 'SCRIPT87: Could not complete the operation due to error 8070000c.' at vlc.js (388,29).
vlc.js line 388 contains 'var id = plugin.playlist.add(uri, uri, options);'.
Internet Explorer shows VLC docked; a couple of its controls do work but not its play button.
The VLC plugin for Mozilla Firefox on Linux works fine.
However, another explanation might be that the Videolan site uses a different methodology that circumvents some other Microsoft issue.