Have you had streaming music clip out with chord Dave?

Does the music cut out or is it just the display on the DAVE that goes blank without interrupting streaming? Not clear from your post.
If you get the music interrupted then try rebooting the streamer. Power off, unplug, wait a bit, connect power and boot it up. If it doesn’t help, keep streamer on and reboot the dac then the mscaler.

1. Are you using proper digital cables between mscaler and DAVE? These are supposed to be 75ohm Digital BNC. Not regular RCA interconnects with BNC adapters.
2. Do you have upsampling enabled in the streamer? If so, disable that option.
3. what interface is used to connect streamer to mscaler? Is it USB? Is the USB cable working properly? Have you tried another USB?

4. Have you tried streamer to DAVE direct without mscaler in the setup? Does the issue persist without the mscaler in your system?

please list streamer make and model, usb cable make and model, digital cables make/model, streamer settings and if you use Roon or not.
Also list Ethernet cable and setup - speed, switches, etc

There’s no possible way you can connect the Mscaler to DAVE via XLR. The connection should be made using two BNC cables. So how are you connecting these two components together - Mscaler to DAVE.

Next, check Lumin settings and turn off resampling/upsampling.

Also make sure the only digital output from Lumin to Mscaler is USB. You shouldn’t have any other digital cables in the Lumin. In the Lumin menu select USB under Digital Audio Output Settings. All other connections should be set to Off. 

Refer to manual here

https://www.luminmusic.com/manual/general-settings.html

Make sure settings in Lumin are correct. Start there. 
Then take the mscaler out. Go from Lumin direct to DAVE via USB. Eliminate one potential culprit at a time. 

And turn Leedh volume off in Lumin. 

Is there a network switch in the chain? Or a copper to fiber optic Ethernet converter?