Certain Atheros wifi NIC drivers failing to operate in HT40 with DD-WRT

[tatsuya46]

With all builds of DD-WRT including latest r16214 certain wifi card drivers, being specific, most if not all of the current Atheros drivers for all Atheros wireless NICs in all laptops, will not operate in HT40 mode with DD-WRT. N 150 cards get slowed down to 65Mbps and N 300 get slowed down to 130Mbps. This is with any reg domain and any channel and of coarse channel width on turbo 40MHz. We have no choice but to downgrade to the latest Microsoft driver in order to get the proper link rates.

This is present with the DIR-825, DIR-615, WNDR3700 and probably several more units. The stock firmware connects all wireless NICs with ANY drivers at the proper rates and never drops.

The newer drivers are detecting a problem with the DD-WRT AP and forcing down to HT20 mode, only DD-WRT is doing this with modern Atheros NIC drivers, not stock firmware.

[tatsuya46]

The following channels also have issues:

Ch 1: Forces HT20 with all clients using any NIC drivers Ch 3: Highest TX power, but also forces HT20 with all clients using any NIC drivers Ch 5: Cuts TX power in half or more Ch 6: Control channel doesn't seem to work, inSSIDer still says 6 + 2 if control is lower or upper Ch 11: Cuts TX power in half or more (<- this one could be by reg domain)

[dorsey]

I can also confirm this issue, running 14929 (latest stable version for my D-Link DIR-825). Selecting any channel in HT40 and watching the result in inSSIDer shows the channel being 40MHz wide briefly then drops to 20MHz after a bit.

[andhavarapu]

when I set dynamic channel widths (20MHz/40Mhz) my devices had troubles connecting. Works like a charm with normal 20MHz (build 18007)