RAX120 - Much slower speeds with AX enabled using an iPhone 11 Pro

[elelunicy]

So the iPhone is the first and the only Wi-Fi 6 client I have, and right now the wifi speeds are much slower with AX enabled (I'm on firmware V1.0.1.90).

AX enabled:

Link speed: 1201 Mbps, Down: 481 Mbps, Up: 298 Mbps

AX disabled:

Link speed: 1083 Mbps, Dowm: 661 Mbps, Up: 522 Mbps

Not only that, AX is also less stable. dropping to as low as below 100 Mbps occasionally, while AC basically never drops below 400 Mbps. Is this supposed to happen?

[avtella]

Can’t comment about the iPhone 11 but I have 3 laptops with the Intel AX200 WiFi internal card I can see up to a 10-20% gain on ax depending on location and signal. Mostly it’s similar in average to low signal situations. Only issue I’ve seen is that for me uploads can hit upwards of 1280+ Mbps but downlink throughout is like half of that when doing file transfers to and from my NAS or even the router’s USB storage.

As the phone is quite new it could be either a phone side issue or a compatibility issue between the two devices. File an issue report with Netgear.

[elelunicy]

I've downgraded the firmware to V1.0.0.84 and now the speeds are much better. I'm getting 726 Mbps down and 600 Mbps up. However, the link rate seems to never reach the theoretical max of 1201 Mbps. Instead it's stuck at 1020 Mbps.

[elelunicy]

Seems like it's stuck at 1020 Mbps because that's the max link rate with 80mhz channel, 1024-QAM, 3200ns guard interval. I've seen the link rate dropping down to 918 Mbps, 816 Mbps, 735 Mbps. 612 Mbps and these are all link rates with 3200ns guard interval. Before downgrading the firmware I could achieve 1201 Mbps as that's the max link rate with 800ns guard interval.

Now the question is: why is the guard interval 800ns on V1.0.1.90, and 3200ns on V1.0.0.84? The phone is losing 15% throughput because of this.