MinimServer w/Bubble UPnP Won't Play FLAC

[funkyblimp]

The only time that Bubble UPnP will not stream FLAC 44.1 to my Galaxy S5 phone is when I am on the T-Mobile 4G network.

When I am at home on Wi-Fi, I get FLAC 44.1 via Bubble UPnP running on top of Universal Media Server.

When I switch to a 4G mobile network, I can only get MP3/128kbps.

The metadata for any given track looks like this when on 4G:
http:\\127.0.0.1:57645\external\audio\media\239495.mp3

This suggests to me that the FLAC was transcoded to a low bitrate MP3 long before it ever hit my phone.

Every setting on Bubble UPnP is set to avoid all needless transcoding and all settings that include a bitrate are set to "original". Experimenting with those settings (and others) made no difference; I always wind up with a low bitrate MP3.

Are there any user-configurable settings in MinimServer that I should be looking at?

Am I trying to do something that is currently technically impossible?