[SOLVED] Radio Station switching bug

[pepitop]

Hello Community,
I would like to re-open this thread. The reason is I am experiencing the same issue as what @dad33 described when opening this thread.
- Symptoms: after changing 6 or 7 times a radio station, I loose my audio. The system is still up and successfully connects to radio stations. The radio time counter in the main panel goes on, I can change radio statio, but no dound...
- HW: rpizeroW, rpi3A+, rpi3B, rpizeroW2. Always with a USB DAB branded ugreen (I have several and it happens with all of them, regardless the rpi).
- Key note: like the OP of this thread, my router is a FritzBox. Although I have been able to reproduce this issue with other routers behind.
- Bonus: I tend to keep the system on 24h. No matter for how long the session has been on, the bug reproduces. Even if I have just rebooted the device.
- Things I have tried without success:
>>Re-scanning the radio stations with  https://www.radio-browser.info/, as suggested by the OP.  
>>Restarting servers with moodutl command.
>>Unplugging/plugging the usb DAB.
>>Restating MPD.
>>Changing various audio configurations: MPD DSD support format (native vs DoP); enabling/disabling MPD SOX resampling; changing audio output (hw vs sw); changing ALSA output mode (plughw vs hw).

Any ideas from the community would be highly appreciated. This bug has been living with me since I started using Moode, more thank 5 years ago...
Thank you in advance.

I'm not able to repro after starting at the top of the Default Playlist and clicking or skipping to each of the 51 radio 
stations but I did discover that the URL's for 2BOB and Czech Radio Classical need to be updated :-)

The symptoms you describe suggest some sort of network issue, possibly really slow connect handshakes from one or more stations or some other oddness.

Try the station scanner in moodeutl and see what it reports or if it hangs on a particular station

Code:

moodeutl -u
moodeutl -U

#
-u             Check radio station urls for playability
-U             Check station urls, list only unplayable

Thank you @Tim Curtis for the tips and explanations.
Following a lot of trial and error, I managed to solve my problem.
Just in case it helps other users, the bug was caused by the usb DAC I was using, a 'UGREEN extern TRRS usb to 3.5mm audio jack". After its replacement for another DAC I now enjoy switching radio stations flawlessly...
What a great audio streamer Moode is!!!