Problem getting TTS or play MP3 to work from Home Assistant to LMS 8!

Hello!

The problem is to get TTS (text to speech) to work from Home Assistant to LMS 8 (piCorePlayer installation).
After much help in the Home Assistant community, the problem seems to be on the LMS side.

What I did was to put two testfiles:
- tts-testfile with 32kb/s CBR MP3 which is 435KB in size
- music-MP3 with 192kb/s CBR from LMS server
into the webserver-folder of Home Assistant

My Home Assiatnt is only available via https:
https://xxxxxxx.duckdns.org:8123 (valid Let's Encrypt certificate)
https://192.168.178.108:8123 (there will be the same Let's Encrypt certificate but it doesn't work as this is no name)

So my files are available under:
https://xxxxxxx.duckdns.org:8123/local/mytestfile.mp3
https://xxxxxxx.duckdns.org:8123/local/mymusic.mp3

If I am using these URL in Safari on my Mac I am getting both files without any problem to play.
When I am using:
on my picorePlayer LMS Pi 4 I am getting this:
The IP address was the current external IP address of my router, so this is correct!
and the file is completely on the Pi:
So the normal connection from the LMS Pi to the Home Assistant Pi is working!

Then I tested these files in LMS. I switched on one Radio station to hear sound coming through the speakers.
Now I opened the URL from above in the Radio-URL dialog:

and:


So the connection itself is working, but for both files only the seconds are counting and the bar goes round and round, but there is absolutely no sound. I also set the volume to max but nothing can be heard.
There is also no single error message in the LMS log!
LMS seems to correctly open the files, as the MP3 tags with cover are shown without any problem, but why no sound?

So what am I doing wrong here? Is this a LMS problem?

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