RT-AC68U 5ghz Repeater Issue

[fadsarmy]

Hi, I'm trying to set up the RT-AC68U in repeater mode. My primary router, RT-AC5300, is broadcasting 2.4ghz and 5ghz networks. When I set the RT-AC68U in repeater mode and scan for new networks, it usually doesn't display the 5ghz frequency of the primary router or any other 5ghz networks around me so I'm forced to enter the 5ghz network ssid and password manually and then it connects fine. This is particularly the case in repeater mode after scanning for networks after the RT-AC68U has been reset to factory defaults or when the RT-AC68U is already functioning in repeater mode and is connected to the 2.4ghz frequency of the primary router. My ac wifi card clearly displays all the 5ghz networks around me so I know there are many present. I've tried this with several RT-AC68U units and they all behave like this. I also tried setting up the RT-N66U in repeater mode and it too has this problem.

I contacted Asus and they said they couldn't replicate the problem.

Any opinions would be welcome.

 

[ColinTaylor]

I've also noticed this with the N66U and the AC68U (although I don't use repeater mode). It's been that way with every firmware version I've used.

I discussed it briefly with @john9527 but we didn't reach any solution.

The problem as far as I can tell (and why Asus couldn't replicate it) is linked to the region of the router. With the router configured for US the scanning works, but configured for EU it doesn't:

# wl -i eth2 scan
wl: Scan Rejected
# wl -i eth2 scan -c 36
wl: Scan Rejected
# wl -i eth2 scan -t passive
wl: Scan Rejected
# wl -i eth2 scan -t active
wl: Scan Rejected

# wl -i eth2 country US
# wl -i eth2 scan -t passive
# wl -i eth2 scanresults | grep ^SSID
SSID: "TP-LINK_5DD3_5G"
SSID: "VM5692010"

N.B. Scanning works fine on 2.4GHz.

EDIT: From the little I've been able to find on the internet this is a limitation of the Broadcom radios. Apparently they don't have a monitor mode so to perform a scan they have to be changed from AP to STA. I've tried this and it works , but unfortunately it disconnects all of the clients in the process . Also, trying to switch back to AP mode doesn't work meaning that I have to restart the entire wireless subsystem.

Of course this begs the question; If monitor mode isn't meant to work how does the Asus successfully do it for 2.4GHz and US 5GHz devices.

 

[fadsarmy]

I've also noticed this with the N66U and the AC68U (although I don't use repeater mode). It's been that way with every firmware version I've used.

I discussed it briefly with @john9527 but we didn't reach any solution.

The problem as far as I can tell (and why Asus couldn't replicate it) is linked to the region of the router. With the router configured for US the scanning works, but configured for EU it doesn't:

# wl -i eth2 scan
wl: Scan Rejected
# wl -i eth2 scan -c 36
wl: Scan Rejected
# wl -i eth2 scan -t passive
wl: Scan Rejected
# wl -i eth2 scan -t active
wl: Scan Rejected

# wl -i eth2 country US
# wl -i eth2 scan -t passive
# wl -i eth2 scanresults | grep ^SSID
SSID: "TP-LINK_5DD3_5G"
SSID: "VM5692010"

N.B. Scanning works fine on 2.4GHz.

EDIT: From the little I've been able to find on the internet this is a limitation of the Broadcom radios. Apparently they don't have a monitor mode so to perform a scan they have to be changed from AP to STA. I've tried this and it works , but unfortunately it disconnects all of the clients in the process . Also, trying to switch back to AP mode doesn't work meaning that I have to restart the entire wireless subsystem.

Of course this begs the question; If monitor mode isn't meant to work how does the Asus successfully do it for 2.4GHz and US 5GHz devices.

Thanks Colin for your detailed reply. I have noticed that after successfully connecting manually to the invisible 5GHz frequency of the primary router in repeater mode, the 5GHz networks now become visible after rescanning.

 

[ColinTaylor]

It all seems very strange and it doesn't help that all the wireless code is closed source now.

What region is your router, US, EU?
Are you using active or passive scanning?

 

[fadsarmy]

It all seems very strange and it doesn't help that all the wireless code is closed source now.

What region is your router, US, EU?
Are you using active or passive scanning?

EU, I think, came with UK plug, bought from Scan. I don't think there's an option for active or passive scanning. How do you perform an active vs passive scan?

 

[ColinTaylor]

Thanks for the info.

I don't think there's an option for active or passive scanning.

I've just realised that you're probably running the stock Asus firmware whereas I'm running a variant of Merlin's. So I have an additional screen that you don't, Site Survey, with active and passive scanning.

 

[fadsarmy]

Reply from Asus:

Thank you for your email.

We have forwarded it to our headquarters, however no solution has been given, as it appears to be a firmware issue. Which would require it to be fixes in a future patch.

So for now, we would suggest the work around of entering the ssid etc manually.

As once this is set, it no longer poses an issue, If I understand correctly?

Kind Regards,
Peter S.

ASUS UK Support team