Thank you for comment.
I have been thinking about this almost all day.
Player device is identified by friendly name of UPnP device. On the other hand, the decision to use IPv4 or IPv6 is based on the USN name during the SSDP process (after which the friendly name is resolved).
Unfortunately, some devices change their own USN names dynamically (The same is true for IP addresses). Therefore, it is not possible to remember whether IPv4 or IPv6 is preferred for each USN name.
The ability to specify IPv4 or IPv6 preference is unfortunately very difficult.