Hi,
I'm afraid none of what you posted from the logs can account for your issue.
Easiest way to debug it is by providing a URL to where a player is embedded.
You can do that by going to KMC, select an entry and in the "Actions" select box choose "Preview & Embed", in the new screen that will open, you'll see a link under the label "View a standalone page with this player".
If your ENV is not accessible from the outside, then open your browser's dev tools, click on play and check both the "Console" and "Network" tabs for errors, in parallel to running kaltlog from the shell.
Once you've found something, it will be much easier to continue the investigation.