40MHz mode doesn't work @ 2.4 GHz (WNDR3700 WRT400N)

[antsh]

There have now been several reports in the forums that 40MHz mode doesn't work on the 2.4GHz radios on the WNDR3700 and WRT400N. I can confirm this using an Atheros 9220 card on a windows xp sp3 machine as the client, and using the atheros utility.

With the stock Netgear firmware, the client picked up both a control and extension channel on the 2.4GHz band. In my case it was control: 1 extension: 5. With DD-Wrt, only the control channel is picked up. This is independent of the mode set in settings. Whether it be FULL, DYNAMIC, or TURBO, only the control channel is visible.

The 5GHz radio works at 40MHZ no problem, both a control and extension channel is picked up and links at 300Mbps.

Since both these routers use the same chipset and radios, and I believe a similar config for DD-WRT, I assume the issues for both are related. Let me know if more details might be needed to diagnose.

Thank you in advance for all your hard work!! It is very much appreciated and not mentioned enough.

[skydiver]

I can confirm this on my Netgear WNR834bv2. In 40MHZ mode i get a stable 270mbps connection. But throuput is the same as with the 20MHZ mode (130mbps). About 35-40mbps . Tested with an Intel 5100 AGN card and windows XP (NG-Mixed mode)

[antsh]

Your issue seems a bit different. 40MHz mode on these routers doesn't turn on at all. The max connection rate achieved is 130mbps.

[skydiver]

Hmm, i get a 270mbps connection rate (40mhz). But the real throuput is the same as with 130mbps (20MHZ) I have no problem to get the 40MHZ connection, but it`s useless. It don`t work as expected. It should be 60mbps real throuput minimum at this connection rate. So i think it`s similar to your problem. I´m using BS mini build 14684 kernel 2.4 .

[antsh]

Okay, and update after a little more investigation. The client does see that my WNDR3700 is broadcasting both a control and an extension channel. It connects for a split second at 300mbps and then drops down immediately to 130mbps. The 5GHz radio doesn't show this symptom, it works flawlessly.

Also, the channel selection for the 2.4GHz radio seems to be acting very weird when selecting 40MHz mode. If lower is selected for the control channel only channel 4 is available. I would like to set 1 to control and 5 to extension, why is this not possible?

[skydiver]

Replying to skydiver:

Hmm, i get a 270mbps connection rate (40mhz). But the real throuput is the same as with 130mbps (20MHZ) I have no problem to get the 40MHZ connection, but it`s useless. It don`t work as expected. It should be 60mbps real throuput minimum at this connection rate. So i think it`s similar to your problem. I´m using BS mini build 14684 kernel 2.4 .

My issue is resolved with using Eko broadcom build 14826. I`m able to get 60mbps throuput with the 40MHZ modes now. Thanks.