Asus RT-AX88U and OFDMA/802.11ax MU-MIMO and AX200 Adapter

[Khun_Doug]

I have the Asus RT-AX88U wireless router. I have two PCs that have the Intel AX200 adapter. One is the aftermarket adapter that I added to an I7 system that is primarily a Kodi HTPC. The second PC has an Asrock X570 Creator motherboard with an AX200 adapter onboard. Both PCs connect properly to the router using 802.11ax. I can see the clients are using 160 Mhz wide links and the speeds are 1200 MB and higher.

The issue is with the OFDMA/802.11ax MU-MIMO setting on the router. If I change this setting to anything other than DL OFDMA Only, such as the option to use MU-MIMO, the adapters lose their throughput in copy actions. This also extends to the 2.4 GHz band, where the default is for this to be disabled.  They PCs behave as though they are only connected at 802.11ac speeds if use anything other than the defaults.

Does anyone have any experience with a router than offers various settings for the OFDMA/802.11ax MU-MIMO? This might be something better brought up on an Asus forum. The reason I post it here is because Intel has the only AX200 adapters that I am aware of, or at least when I bought the router.

[Esteban_D_Intel]

Hello Khun_Doug,

Thank you for posting on the Intel® communities.  

To better assist you, I would appreciate if you could provide the following information:

• What other router settings have you tried?
• Have you changed the settings of the wireless adapter?
• What is the driver version installed? Is it the same in both systems.
• Have you tried checking with ASUS* for recommendations?

Please run the following tool and attach the reports generated.  

. Intel® System Support Utility (Intel® SSU)  download link:

https://downloadcenter.intel.com/download/25293/Intel-System-Support-Utility-for-Windows-  

1. Open the application and click on "Scan" to see the system and device information. 
2. By default, Intel® SSU will take you to the "Summary View".  
3. Click on the menu where it says "Summary" to change to "Detailed View".  
4. To save your scan, click on "Next", then "Save".  

Esteban D. 

Intel Technical Support Technician

[Khun_Doug]

The SSU file is attached. As for your questions:

• What other router settings have you tried?

I tried enabling the OFDMA/802.11ax MU-MIMO setting on the 2.4 GHz band and that has negative effect. On the 5 GHz band the OFDMA/802.11ax MU-MIMO defaults to DL OFDMA Only. Any other setting seems to have a negative effect. The negative effect is that the clients only operate at half their speed, as though the link drops back to AC.

• Have you changed the settings of the wireless adapter?

I tried setting Throughput booster on and off. It really seems to make no difference when copying from an AX source to an AX destination through the AX enabled router.Both clients connect at 160 MHz wide and the copy speed is about what I expect.

• What is the driver version installed? Is it the same in both systems.

The driver on both systems is 21.110.1.1.

• Have you tried checking with ASUS* for recommendations?

I just reactivated my Asus forum account to see if others have reported this. There appears to be no discussion about OFDMA/802.11ax MU-MIMO. In the router's wireless log it does show the link as AX, and the MUBF (mean forming) flag is turned on. I really believe that Asus got the firmware to work for AX with the defaults, and going beyond that is trouble. I plan to post this on the Asus forum as well.

[Esteban_D_Intel]

Hello Khun_Doug,

Thank you so much for your response.

After checking the information provided, we can see that in terms of software/drivers you are up to date. And I consider that you have performed enough troubleshooting to determine that this behavior could be related directly with the router’s configuration.

As this negative effect occurs only after changing the router settings we consider that contacting the router manufacturer for further recommendations to avoid this issue would be the best thing to do.

 Hopefully they will provide certain configuration to increase performance and stability with both computers.

Another thing that I would recommend checking is a possible issue with the antennas.

Additionally, I would like to share with you the following article where you can check our Advanced Intel® Wireless Adapter Settings

Hopefully, the router manufacturer may release a firmware update for the router that will improve the functionality between devices.

As previously stated, we consider that contacting the ASUS* would be recommended based on the nature of this issue.

Please check with them and I hope that they will be able to resolve this issue.

If you need any additional information, please submit a new question as this thread will no longer being monitored  

Esteban D. 

Intel Technical Support Technician