Just some technical things …
- AC with VHT goes up to 866Mbps interface rate with 2-stream on 80 MHz bandwidth (using 256QAM). The well known limit.
- AX with HE goes up to 1024 QAM encoding and has wider channels (see mcsindex table for interface rates
- Other stream combinations are in the mcsindex table.
- What is the AC 80+80 (primary + secondary) doing, in performance ?
In practice, and that practical limit is strong with MT classic drivers, the net data transfer rate is reduced because the air-time is shared among all transmitters in the channel, and the channel-contention process requires gaps between successive transmissions.
With small transmission packets, the gap loss for every transmission in VHT becomes very important with higher rates. Classic MT drivers have small A-MSDU (MPDU) and small A-MPDU, and don’t use the standard large transmissions.
http://forum.mikrotik.com/t/wifiwave2-expected-performance/160075/3 The impact of this on the data rate can be calculated
What is AX , with HE instead of VHT doing with this? https://www.extremenetworks.com/wifi6/what-is-80211ax/