Posted: Mon Feb 02, 2015 13:31 Post subject: Channel Width HT40 does not work on TP-Link TL-WR841N(D) 8.x
I just bought TP-Link TL-WR841N(D) 8.x and found the DD-WRT v24-sp2 (01/29/15) std - build 26081 is buggy on wireless Channel Width HT40 (802.1n with 2.4G).
All the following cases with Channel Width = Wide HT40 (20+20 MHz) and Wireless Network Mode = Mixed and Regulatory Domain=HONG KONG (1-13)
1) Wireless Channel=11, Extension Channel=Lower
but the wireless status page show Channel=11 + 15 (2462)
(I chose Lower, but the extension channel is 15, which is Upper, and HK does not allow 15)
2) Wireless Channel=6, Extension Channel=Lower
but the wireless status page show Channel=6 + 10 (2437)
(I chose Lower, but the extension channel is 10, which is Upper)
3) Wireless Channel=6, Extension Channel=Upper
but the wireless status page show Channel=6 + 2 (2437)
(I chose Upper, but the extension channel is 2, which is Lower)
and most importantly, although the Wireless status page shows Rate=300 Mb/s, but all my my wifi devices (supports upto 450mbps) cannot connect with HT40, only HT20 is enabled (Max 144Mb/s).
Last edited by kelvinlaw on Tue Feb 03, 2015 13:30; edited 1 time in total
The HT40 channel display on the Status-Wireless page has been extensively discussed in ticket 3951, but it looks like BrainSlayer removed the ticket entirely for whatever reason. http://svn.dd-wrt.com/ticket/3951
The bug is still not fixed for Atheros-based routers (showing an Upper extension channel instead of Lower and vice-versa). The fix would be easy, but he considers it incorrect to implement and said repeatedly that it works for him. But you see that it displays it wrong for you and also for others.
I would propose to report your issue in a new ticket on bug trac, but the registration there for new users is also locked, strangely. So yeah, we have no choice, but to switch to other firmwares with friendlier communities (you know which one I'm talking about).
If you choose to still use DD-WRT, then have fun with seeing HT40 channels displaying combinations such as 1+ -3, 2+ -2, 4+0, 11+15 or 13+17 ! As I see it, the situation won't change any time soon... _________________ THERE ARE NO STRANGERS HERE; ONLY FRIENDS YOU HAVEN'T YET MET.
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Thanks for your reply and letting me know that it is not particular issue for my router, but a common issue.
by the way, may I know can you actually get channel width HT40 work? because all my wifi devices cannot get the highest connection rate, 144MB/s at most, and max real data transfer rate above 80MB/s. Is it normal?
Joined: 24 Feb 2013 Posts: 1634 Location: Belgrade
Posted: Tue Feb 03, 2015 14:04 Post subject:
You must use WPA2+AES, check Regdomain... if not sure use channel 6 because it is in the middle of the spectrum... mode NG mixed (only N was broken last time I checked)...
I can confrim the HT40 wireless status bug with Linksys E4200 too. It happens only with K2.6 images.
With K3.x it's correctly displayed.
Current image 28072 but this belongs to all of the last images I had tested.