I'm sorry but I think you are wrong. I updated to the dd-wrt 17798, erased the nvram, rebooted the device and tried a lot of things to get a better coverage. Unfortunately, the transmission power doest seemed capped. If you choose the 40 MHz channel width as shown below, the tx power is actually capped at 10dBm.
$ telnet 192.168.11.1
Trying 192.168.11.1...
Connected to dd-wrt.
Escape character is '^]'.
DD-WRT v24-sp2 std (c) 2011 NewMedia-NET GmbH
Release: 10/31/11 (SVN revision: 17798)
DD-WRT login: root
Password:
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| _ \| _ \ \ \ / / _ \_ _| __ _|___ \| || |
|| | || ||____\ \ /\ / /| |_) || | \ \ / / __) | || |_
||_| ||_||_____\ V V / | _ < | | \ V / / __/|__ _|
|___/|___/ \_/\_/ |_| \_\|_| \_/ |_____| |_|
DD-WRT v24-sp2
http://www.dd-wrt.com
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BusyBox v1.19.2 (2011-10-31 16:56:36 CET) built-in shell (ash)
Enter 'help' for a list of built-in commands.
root@DD-WRT:~# iwconfig ath0
ath0 IEEE 802.11bgn Mode:Master Frequency:2.417 GHz Tx-Power=10 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Power Management:off
Switching the channel width to 20MHz boosts the TX-Power value to 14 dBm.
Based on your comments, I triple checked the rates, signal strength and SNR for a few clients located in various place in my house and I can assure you that the signal is weak whatever settings I use. Trying to set the tx power manually isn't taken or gives an error depending on the value:
root@DD-WRT:~# iwconfig ath0 txpower 15
root@DD-WRT:~# iwconfig ath0
ath0 IEEE 802.11bgn Mode:Master Frequency:2.417 GHz Tx-Power=10 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Power Management:off
root@DD-WRT:~# iwconfig ath0 txpower 16
Error for wireless request "Set Tx Power" (8B26) :
SET failed on device ath0 ; Invalid argument.
With such a weak signal, boosting the antennas doesn't make a big difference.
I will contact support tomorrow, but I really regret having bought this device, especially considering that it's called the AirStation™ HighPower N450 Gigabit Wireless Router - WZR-HP-G450H.
- Matt