Check below important items to be able to enable ensemble operation:
1, HDMI cable connected from Primary VR5 sync out to Secondary VR5 sync in port on lowest DSP module in the rear panel.
2, 10MHz out from Primary VR5 out to Secondary VR5 in
3, VR5#1 and VR5#2 should be connected to the same router or switch through ethernet port
4, Ensemble -2U/4U option is needed based on how many VR5s need ensembled together