WRT1900ACS v2 Channel 100

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jcastle003
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Joined: 23 Apr 2015
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PostPosted: Sun Jan 17, 2021 20:09    Post subject: WRT1900ACS v2 Channel 100 Reply with quote
I was able to get a deal on a WRT1900ACS v2 so I decided to swap out my WRT1900AC. I've been using Channel 100. I noticed my neighbors are all crowded in the lower and upper channels. They're most likely using their router with Channel "Auto" selected. Great for me since it leaves the middle channels wide open for 802.11AC 5Ghz Wifi.

I flashed the WRT1900ACS v2 with the latest DD-WRT (r45454) and configured wifi with the same settings as my old router. All configuration settings were available and seemed to have taken (saved and applied). I monitored which SSIDs would pop up using Wifi Analyzer on my Android smartphone. Only my 2.4Ghz wifi would come up. My 5Ghz wifi on Channel 100 would not. I configured for "Auto" channel on 5Ghz and it came up fine, but was in the crowded upper section of channels (Channel 153 I believe). Tested out a few other middle channels and it would take the settings, but the SSID would never come up. Lower and upper channels work fine.

Anyone have a similar experience with their WRT1900ACS v2? I'm wondering if it's hardware specific to the WRT1900ACS v2 or is my unit defective.

I've swapped back to the WRT1900AC and using Channel 100 with no issues on r45454.
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SurprisedItWorks
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Location: Appalachian mountains, USA

PostPosted: Sun Jan 17, 2021 20:43    Post subject: Reply with quote
Don't know where you are, but in the US only the top and bottom of the 5GHz band are really available. The middle is reserved, I believe, for some radar purpose. Google is your friend here, but if you use 5GHz in the US with 80MHz bandwidth, the maximum available for your router, you have a choice of 36UU or 149UU (there are other ways to specify those two choices).
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jcastle003
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Joined: 23 Apr 2015
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PostPosted: Sun Jan 17, 2021 21:16    Post subject: Reply with quote
I'm in the US. Thanks for the reply. You got me thinking about regulations so I checked on Wikipedia.

https://en.wikipedia.org/wiki/List_of_WLAN_channels#United_States

For US:
"In 2007, the FCC (United States) began requiring that devices operating in the bands of 5.250–5.350 GHz and 5.470–5.725 GHz must employ dynamic frequency selection (DFS) and transmit power control (TPC) capabilities. This is to avoid interference with weather-radar and military applications.[44] In 2010, the FCC further clarified the use of channels in the 5.470–5.725 GHz band to avoid interference with TDWR, a type of weather radar system.[45] In FCC parlance, these restrictions are now referred to collectively as the "Old Rules". On 10 June 2015, the FCC approved a "new" ruleset for 5 GHz device operation (called the "New Rules"), which adds 160 and 80 MHz channel identifiers, and re-enables previously prohibited DFS channels, in Publication Number 905462.[46] This FCC publication eliminates the ability for manufacturers to have devices approved or modified under the Old Rules in phases; the New Rules apply in all circumstances as of 2 June 2016.[46]"

The WRT1900ACS v2 must have been manufactured after June 2016 and has hardware restrictions to adhere to the "New Rules." This is good to know. In my mind, it makes the older WRT1900AC models more desirable since you can still use the middle channels. The TPC restriction for middle channel usage in the US is max 500mW. I'd rather use a channel at lower power with no crowding than competing in a channel using higher transmit power.
msoengineer
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Joined: 21 Jan 2017
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PostPosted: Sun Jan 17, 2021 21:32    Post subject: Reply with quote
go read about wifi channels in the qca wiki and DFS...same applies to you.
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o2bad455
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PostPosted: Sun Jun 26, 2022 21:19    Post subject: Reply with quote
jcastle003 wrote:
The WRT1900ACS v2 must have been manufactured after June 2016 and has hardware restrictions to adhere to the "New Rules." This is good to know. In my mind, it makes the older WRT1900AC models more desirable since you can still use the middle channels. The TPC restriction for middle channel usage in the US is max 500mW. I'd rather use a channel at lower power with no crowding than competing in a channel using higher transmit power.


I confirm that the WRT1900ACS v2 has DFS/TPC channel limitations versus all earlier WRTs, although I wouldn't necessarily assume "hardware" since it may well be a remnant of factory coding. Although most expected channels for the selected Domain (country) are selectable from the 5 GHz channel pulldown in wireless/settings (although unfortunately missing otherwise allowed non-DFS channel 165), the only station that can actually see the ACSv2 when it's using a DFS (radar detection) channel is another dd-wrt router! A quick and dirty check of hardware capabilities can be done from status/wireless/channel survey. Here, my slightly older WRT1900ACS sees 24 channels when using the United States Domain (and works fine on all of them), but the WRT1900ACSv2 sees only 8 channels for the same Domain (and only works on those overcrowded 8, at least so far)! I wonder if there's any way to address this discrepancy?

With an ACS (v1), I can successfully use DFS channels, even with AutoChannel, with radar detection enabled and very low power (14 dBm is about 25 mW). Unfortunately, I've been unable to do likewise with the ACS v2. To make matters worse, I don't think the scanlist option works for Marvell chipsets.

I'd be curious to know which WRT routers are affected by this reduced number of channels limitation:

WRT1200AC - DFS OK

WRT1900AC - DFS OK
WRT1900ACv2 - DFS OK

WRT1900ACS - DFS OK
WRT1900ACSv2 - DFS BLOCKED

WRT3200ACM (original or rev A00 serials 198106...) - ???
WRT3200ACM (9/17+ revs B00/C00 serials 198116...) - ???
WRT3200X - ???

EDIT: Is this related? https://github.com/openwrt/openwrt/issues/9956

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Linksys WRT3200ACM - Marvell
Linksys WRT1900ACS - Marvell
Netgear R9000 - Atheros
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