Bug in Asus firmware - Protected Management Frames not backwards compatible causes 802.11n devices to lose connection

[Hunny Puppy]

I just noticed a bug in the Asus firmware. Using a RT-AX88u with a Denon receiver (X2400) which has a 802.11n card in it.

If I set Protected Management Frames to *capable* (required to use the Agile WiFi multiband feature), then the denon receiver is not longer able to connect to the router. According to the specifications *capable* should allow legacy 802.11n devices to connect to the router, i.e. the protected management frames are optional but it appears that the implementation isn't backwards compatible. I've seen the same behavior on the 2.4 and 5Ghz bands w.r.t to protected management frames. The moment I set it to disabled, the denon receiver is able to connect, when I revert to capable it stops communicating. I've verified this with the Official 386.x and 388.x series firmwares including the latest firmware 3.0.0.4.388.22237

Anyone else noticed this or is there a way to verify this behavior? @RMerlin have you encountered this in your testing?

 

[OzarkEdge]

I just noticed a bug in the Asus firmware. Using a RT-AX88u with a Denon receiver (X2400) which has a 802.11n card in it.

If I set Protected Management Frames to *capable* (required to use the Agile WiFi multiband feature), then the denon receiver is not longer able to connect to the router. According to the specifications *capable* should allow legacy 802.11n devices to connect to the router, i.e. the protected management frames are optional but it appears that the implementation isn't backwards compatible. I've seen the same behavior on the 2.4 and 5Ghz bands w.r.t to protected management frames. The moment I set it to disabled, the denon receiver is able to connect, when I revert to capable it stops communicating. I've verified this with the Official 386.x and 388.x series firmwares including the latest firmware 3.0.0.4.388.22237

Anyone else noticed this or is there a way to verify this behavior? @RMerlin have you encountered this in your testing?

I would assume the Denon adapter does not tolerate setting Protected Management Frames to *capable* (WPA3).

[Wireless] How to improve compatibility of IoT device with ASUS WiFi 6(AX) Router? | Official Support | ASUS Global

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[HarryMuscle]

Most likely a bug in the receiver firmware not the router. Just because it should allow backwards compatibility doesn't mean it's guaranteed if the client is faulty. Heck, I've got an Intel WiFi card that doesn't like certain channels and crashes.

 

[Hunny Puppy]

Thanks, I did report it to Denon to investigate.

So I followed the instructions and disabled all the 802.11ax features and set it to only N mode for maximum compatibility with the N card in the denon receiver. It's still losing the connection with the RT-AX88u router after a few minutes. However when I switch it over the RT-AC86u router it works perfectly. I still suspect there's a firmware issue with the RT-AX88u router. Any thoughts?

 

[tgl]

What shows up in the router's log when connection is lost?

 

[Hunny Puppy]

Strictly speaking it doesn't lose the WiFi connection it appears to have severe packet loss / loss of communications, like maybe 99% of packets. Eventually a packet will get through but there is severe loss of communication with the receiver after a few minutes.

I don't see anything in the Router logs related to the receiver or it's IP.

I just tried something else, in addition to disabling all the ax related features on the RT-AX88u on the 2.4Ghz band I also disabled Explicit beamforming and for now it appears to be communicating normally. But none of these issues exist when using the RT-AC86u, including enabling Explicit beamforming.

Thoughts?

 

[tgl]

I just tried something else, in addition to disabling all the ax related features on the RT-AX88u on the 2.4Ghz band I also disabled Explicit beamforming and for now it appears to be communicating normally. But none of these issues exist when using the RT-AC86u, including enabling Explicit beamforming.

Interesting. I don't know too much about that myself, but in lurking on these boards I've definitely seen beamforming options implicated in various problems. Try leaving it off for awhile to see if that's really a fix or it just coincidentally failed to misbehave right away.

 

[Hunny Puppy]

Scratch that, it's stopped communicating again, even after disabling explicit beam formation. The router is showing that it's connected with a strong signal -45db but it's lost communication with the router (severe packet loss). Tried switching it to the RT-AC86u and it starts working perfectly. Sigh.... I"m getting frustrated and running short on ideas.

 

[tgl]

Sigh.... I"m getting frustrated and running short on ideas.

Yeah, so most likely you are not going to be able to make that device work with that router --- and even if you could, dumbing down the router to 802.11n is throwing away a lot of your investment on that gear. Time to consider alternatives.

IMO, using wi-fi to connect stationary devices like AV receivers isn't best practice to start with. Wi-fi bandwidth is scarce so you should be saving it for your mobile devices. Is there any chance of running an ethernet cable to the receiver? If that's out of the question, maybe you could get a cheap "media bridge" wi-fi device (hopefully more modern-standards-compliant than the receiver itself) to sit beside the receiver and pass data over a short ethernet cable.

 

[Hunny Puppy]

Thanks, yeah I'm looking into options now but I'm a little frustrated at Asus here. I strongly suspect an issue with the Asus RT-AX88u firmware. Even with AX features turned off if it doesn't work while the AC86u does, something with the AX88u firmware isn't right. Is there a way to get Asus's attention to this issue?

 

[ColinTaylor]

Is there a way to get Asus's attention to this issue?

Use the Feedback option (Administration - Feedback) available in the stock firmware's GUI.