1. Groupable SMs count
On Monitor -> Wireless page new column is displayed - Groupable STAs.
Current screenshot represent each of 2 SMs has other as a groupable one.
With higher number of groupable SMs higher Downlink MU-MIMO gain is expected.
2. MU-MIMO Throughput Chart
On Monitor -> Throughput Chart green chart represent Downlink Traffic runniing in MU-MIMO mode.
Blue Chart represent Total Downlink traffic which may contain MU-MIMO trafffic and SU-MIMO traffic.