LMS 8.1.1 - 1610364019 on RpI -> UPNP Media-Interface not working after reboot

Hello Folks,

i'm faced to a strange problem on my LMS 8.1.1 installation, which i am running since 2 weeks now.

The previous installation (8.0.0) was running on my Synology DS218j and didn't face this issue:

After Rebooting my Raspberry PI 4b (with only the acutal raspbian-os installed an the LMS 8.1.1. 1610364019, my 3rd-Party UPNP-Internetradios cannot find the LMS as "Mediaserver"...

After manual restarting the lms (by installing a plugin etc) or via the "systemctl restart" command in raspbian, the LMS appears immediately on all my 3rd-Party devices.

Beside of this, the LMS works as intended (even after rebooting).... This issue only affects the UPNP-Mediainterface...

Is this a known problem? Any ideas?

Thank you all for your help :-)

Cheers, Tob!