Asus RT-AC56U 5 Ghz network works only in 20 Mhz band

[Tume82]

Hi,
I have RT-AC56U and the problem is that clients can connect to 5 Ghz network only when the Channel bandwidth have been set to 20 Mhz (any other setting doesn't work: 20/40/80 or 40 or 80).
SSID is visible on the clients when the band is set to anything else than 20 mhz and i can try to connect to it, but i get connection error.

I have tested changing the channels and using different bands, but only the 20 mhz band seems to be working.

What i have also tested is to change the wireless mode and regulation mode, but those didn't help.
I had this same problem already before when i was using the latest Asus firmware and after the upgrade to Merlin the same problem exists.

What i have understood is that using the 20 mhz bandwith has will cause make the AC useless, because it uses wider bandwiths. Is this correct?

I can also choose the channels 36, 40, 44 and 48, but should be normal thing because i am located in europe.

More info:
-Wireless mode is in auto
-I have tested this with Lenovo T440s, Sony Z3s and Nexus 7.
-Current software on the router is Merlin 378.55

 

[charlie2alpha]

Strange, using it on channel 36, both my Nexus 9 and an Asus USB-AC56 connect fine at the maximum link speed of 866MBps. Did you try a factory reset (without restoring your config)?

Sent from my Nexus 9 using Tapatalk

 

[Tume82]

Strange, using it on channel 36, both my Nexus 9 and an Asus USB-AC56 connect fine at the maximum link speed of 866MBps. Did you try a factory reset (without restoring your config)?

I did factory reset before the firmware upgrade, but i guess i will give it a try once more. Is it enough to do the factory reset on the management web page?

 

[charlie2alpha]

I did factory reset before the firmware upgrade, but i guess i will give it a try once more. Is it enough to do the factory reset on the management web page?

That's how I always do it. After the reset don't restore any settings, just setup the Wifi and check.

Sent from my Nexus 9 using Tapatalk

 

[Tume82]

Hi,
Restoring the factory default settings didn't help.
These are the settings after the reset:

Anything wrong with these?

 

[RMerlin]

If you have connectivity issues then disable Beamforming support.

 

[drabisan]

My 2c here: why Asus has a default long preamble?
In an N or AC environment preamble should be short and not long, cause nobody wants long time used by a packet that ensure compatibility with really old clients.

 

[Tume82]

I tried to disable both ac and universal beamforming, but problem still exists. 5ghz starts working right after I set the bandwidth to 20 Mhz. How many channels should there be to select from? I only have 36, 40, 44 and 48. Is that normal?

 

[L&LD]

Just need to mention that factory reset before flashing new firmware is pointless. The reset to factory firmware and manually and minimally setting up the router to connect to your ISP and secure the router afterwards should be done only after flashing the new firmware you want to use.

I also recommend using new ssid's too. This will effectively create a new network for the router and all devices and force them to use any special or different microcode the new firmware may depend on.

I did factory reset before the firmware upgrade, but i guess i will give it a try once more. Is it enough to do the factory reset on the management web page?

 

[RMerlin]

My 2c here: why Asus has a default long preamble?
In an N or AC environment preamble should be short and not long, cause nobody wants long time used by a packet that ensure compatibility with really old clients.

Probably for increased compatibility out of the box.

 

[Tume82]

Just need to mention that factory reset before flashing new firmware is pointless. The reset to factory firmware and manually and minimally setting up the router to connect to your ISP and secure the router afterwards should be done only after flashing the new firmware you want to use.

I also recommend using new ssid's too. This will effectively create a new network for the router and all devices and force them to use any special or different microcode the new firmware may depend on.

Thanks for pointing that out. I have reseted the router and also set up new SSIDs put that doesn't seems to help in this case. I changed the SSIDs because i though that problem is cause by he clients (mostly because the android devices make backup of the SSIDs and remember those and i thought that it can cause problems when settings are changed).

Could this problem be caused by interference on the 5 Ghz bandwidths? 80 Mhz bandwidth would use all the 4 channels and i guess if one of those doesn't work it could cause problem?

I have used the wifi analyzer on android and at least there isn't any access points on 5 Ghz network, but maybe something else is causing interference?

 

[charlie2alpha]

Interference at 5GHz? Highly unlikely to be honest, especially if you testing with the client next to the router. When exactly did this start? Was it working with a previous firmware?

 

[Tume82]

5 Ghz was working at least sometime just after i took the router from the box and made basic configuration, but problem started after the upgrade to new Asus release of the firmware (i made the upgrade from the management webpage). I can't recall any changes that by me that could have caused this problem.