You may be confusing MIMO, which has been part of Wi-Fi since 802.11n, with MU-MIMO. 802.11ac standardized MU-MIMO methods and supported downlink (DL) only. 11ax introduced Uplink (UL) MU-MIMO. Both forms of MU-MIMO must be supported on both STA and AP.Wait what ?! No Mimo support for AX as opposed to AC wave 2 ?!?!?!….