Disabling Autologin Breaks Sound

[spamsink]

I have a NanoPi R6C.  The vendor, FriendlyElec, has provided for this 
device an image of Debian 11, which I have installed.  The image is 
configured to use LightDM, and autologin is enabled for user pi.  Out of 
the box, the sound works.  If I disable autologin then this breaks the 
sound.

With autologin enabled, pulseaudio starts as user pi.  With autologin 
disabled, pulseaudio starts as user lightdm.  Then user pi attempts to 
start pulseaudio and this fails with the error message "bind(): Address 
already in use".  After that I can get the sound working again with the 
command "systemctl --user restart pulseaudio".

What do I need to do in order to get pulseaudio to start up correctly 
when autologin is disabled?  I would be grateful for any assistance.