BE9300 Broken With 4kQAM Rate Set On BE200

So this is an interesting and very specific phenomenon I've narrowed down.

The BE200 from intel and the BE9300 from Netgear completely bomb out their rate set negotiation when the signal is perfect.

Yup, this means what you think. Moving the antenna further away or in a suboptimal position to force a lower RSSI so that 1024 QAM or lower is negotiated gives the expected bandwidth.

It appears that one of the devices gets confused or "stuck" on properly allocating the available resource units or doesn't have 4kQAM properly mapped into a rate setting table.

I've checked this repeatedly with spare wifi antennas, moving the PC around, and overzealous usage of iperf 3.2.0 against a wired PC also connected to the BE9300 as well as iperf on an iphone 16.

The iphone 16's themselves appear fine under all conditions, but that's seemingly because they only support 160mhz wide connections and 1024QAM. Yup... apple runs their newer iphone 16s and 17s at 6E speeds, and it's on their official website as per https://support.apple.com/guide/deployment/wi-fi-ethernet-specifications-apple-devices-dep268652e6c/web.

This is what it looks like when it's working and forced to a slightly weaker signal around 53db.

This is what it looks like when the signal is stronger and 4kQAM is utilized on the link.

As you can see the rate set for the uplink swaps to a 4kQAM mode while the downlink crashes and almost appears to be using the BPSK-DCM and BPSK-DCM-DUP rate sets listed as MCS indices 14 and 15 in the rate-set table for wifi7, instead of 12 or 13 as it should be.

Either that or my other guess is the RU allocation "gets stuck" or confused under this specific scenario for some unknown reason.

The BE9300 is using the latest 1.0.6.16 firmware, and the BE200 has been updated to the 24.20.2 drivers, although this has been an ongoing situation across multiple driver versions.