UPnP server can't be found anymore

  • Just installed LibreELEC 8.1.1 on an Intel machine to act as client of a main Kodi installation on a Windows machine.

    LibreELEC client is connected to TV through HDMI.

    Established connection to the Kodi server through UPnP - no problem to find it.

    Working normally, but no sound. Noted that audio output was not set to the HDMI option, so changed to that - sound appeared.

    As I powered up again, could not connect to the UPnP server anymore.

    Removed the UPnP connection and tried to add it again, but no UPnP server found.

    Important: connectivity to the PC that has the main Kodi installation does exist - I can browse its shared folders through SMB.

    Tried to restart the main Kodi but that did not fix things.

    What may be happening?