Channel and bandwidth for 2.4 ghz access point

[Brian John]

I have an Asus RT-AC3200 (2.4 ghz and 5 ghz) as my primary router and an Asus RT-N16 (2.4 ghz only) as an access point. Both devices are using the same SSID for 2.4 ghz. I have read the excellent access point setup guide on this website and have configured the devices accordingly: http://www.smallnetbuilder.com/basi...onvert-a-wireless-router-into-an-access-point.

However, I'm confused about a couple of items that are not addressed in the article: channel choice and bandwidth. On both the router and access point the bandwidth is set to "20/40 MHz" and channel "auto" by default. The devices both have "20 MHz only" or "40 MHz only" available as bandwidth options. The routers are close enough together that they could create interference between each other.
* Should I be using the same channel on both devices?
* What bandwidth should I be using?
* Can someone help me understand what "20/40 MHz" means?

It seems like if both devices use 40 MHz then it won't be possible to prevent interference between them. I've experienced a lot of bandwidth/connectivity issues on this network, I'm not sure if these settings could be related but any help is appreciated!

 

[sfx2000]

For multiple AP setups in 2.4GHz mode - wide channels will cause interference across the two AP's as we only have 3 non-overlapping channels in 2.4GHz.

So the recommendation is to run both AP's in 20MHz channels only - this will keep them from interfering with each other (and the associated clients to those AP's).

As for channel selection - depends on your environment (e.g. neighbors) and how crowded your 2.4GHz is - I would take the neighborly way out and put them both on the same channel, as the AP's will coordinate with each other, or if you've got some free space, can consider putting one perhaps on one channel, and the other on another...

Single channel can help with roaming from one AP to another in many cases - see what works best for you there..

Location of the 2nd AP relative to the primary - too close together and there is no benefit as the clients will camp on one, and that AP will interfere more with the primary - try to get about 20dB RSSI difference between the two AP's - a decent swag estimate, about 25 feet away from the primary AP should be enough depending on construction of the building (sheetrock, not bad, old school plaster/lath with chickenwire, might be a problem, lol).

Keep in mind that WiFi is not the only thing that runs in 2.4GHz - Bluetooth is by far the next most common radio out there, and it can be impacted by strong wifi in close proximity - esp. for keyboards/mice and mobile headsets.

Final note - since you've gone common SSID across the two AP's in 2.4GHz, make sure they are both using the same authentication methods (WPA2-AES is strongly recommended), same WPA2 passphrase, and I would suggest setting both the B/G/N mixed, disabling TurboQAM on the RT-AC3200 to reduce client confusion. Again, try the single channel first, and if needed, split the channels between the AP's

 

[Brian John]

This was really helpful, thanks! I have a couple of follow up questions if you don't mind:
* Would it be ok to run the main router in 40 MHz mode and the AP in 20 MHz on separate channels? Not very neighborly I know, but I'm far away enough from my neighbors that I don't think they're picking up any interference from me anyway.
* Do you have a recommended way to measure the RSSI difference between the two devices?

 

[sfx2000]

Very little benefit to running Wide Channels in 2.4GHz, and general guidance is not to do it...

For RSSI - InSSIDer (not free), Acrylic Wifi (Free), WiFi Explorer for Mac, and believe it or not, the Airport Utility for iOS has a scanner built in (hidden in Setting/Airport Utility).