Dropouts indicate network and clocking problems. You should reset both (!) mixers and build your network from scratch. Reset means project, scene and patching (Master Reset). Then start the console first. When the rack mixer is booted up fully, go to Home -> Audio Routing -> Stagebox Setup. The rack mixer should already be seen there. Select Stand Alone and check if the green LED is on, then save this setting in a project and store the generated scene separate (scenes are not stored automatically; use a name corresponding to the project).
The reason for this procedure is to enable the mixers to use stagebox modes again. The three network presets do work reliably, but they need to be established "clean". Also, using the stagebox modes automatically chooses the right clocking of the network. Monitor Mode and Stand-Alone Mode use a different setting than Stagebox Mode.
This should solve your probklem. Please report back. ;-)