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Mixing AP 37xx, 38xx, and 39xx aps in one environment


I have a mixture of ap models in school environments, and it seems as if the clients are showing a preference for 39xx aps over 38xx aps. In adjacent rooms where I have different types, I will have many more connections to the 39xx ap. (there are typically 20-25 chromebooks in each classrooom) and there will be 50-60 connections to the 39xx ap and 15-20 connections to the 38xx ap in the next room. Is this possible? Preventable?

13 replies

Well, you could look at probe suppression and force disassociation at -75 dB. Do you have the power levels set the same on both APs (one isn't blasting both radios at 12 dB while the other is at 5 dB). Do you have any co-channel interference that could be preventing your client from wanting to connect to that AP?
I have probe suppression turned on and forced disassociation at -65Db. Power levels are auto set but are similar on all aps in a given area. Channels are also auto selected but I don't see any problems there.
I guess I'm just wondering if the 39xx aps provide a better looking connection to the clients than the 38xx so they choose that one instead. Or should they be equivalent as far as the client is concerned?
Um, I would assume it would be a better SNR for the other AP. Auto channel and power don't necessarily work all the time. Does the power level make sense? Do you get good RSS from clients connected to the AP and vice-versa?

What channels do you have on the 2.4 ghz and 5 ghz on both APs. What is the SNR for each connection from their respective locations than opposite locations? There can be hundreds of reasons! How dense is your deployment? Also, what is your MBR on the APs?
Also, what is the distance between these APs if you had to estimate?
Have you considered setting up a load balance group between the APs?

It is good practice to keep the APs in a given area the same model if possible, I try and upgrade whole buildings at a time.
It's not really a question of two ap's. It's a pattern throughout the building. We formerly had 3825 aps in every other classroom. Then added 3935 aps in the every OTHER classrooms that hadn't previously had one. So it's a pattern I see throughout the building that the 3935's tend to have more client connections than the 3825's. So load balancing groups would be complicated. Maybe I just need to consolidate 3935's and 3825's by building.
The channels don't overlap, the power levels are similar and seem appropriate (14-16dB), the distance between access points is about 30 feet.
This is what the ExtremeWireless user guide says about load balancing...

You can configure APs that are co-located in an open area, such as a classroom, a conference hall, or an entrance lobby, to act as a load balance group. Load balancing distributes clients across the co-located APs that are members of the load balance group. The co-located APs should provide the same SSID, have Line-of-Sight (LoS) between each other, and be deployed on multiple channels with overlapping coverage.

So I don't think LB is a solution to your problem. Maybe drop the power on the 3935 a few dB. See if that makes a difference.
Agreed. I'll give that a shot. Thanks.
Userlevel 7
Could you please post a screenshot of the client report and filter on the 39xx and then on the 38xx in the next room - I'd like to take a look in the protocol column.
Userlevel 2
Are the client devices MacOS? MacOS devices are configured to prefer 802.11ac over 802.11n. You can read more about Apple's preferred wireless roaming here: https://support.apple.com/en-us/HT206207
Ty Kolff wrote:

Are the client devices MacOS? MacOS devices are configured to prefer 802.11ac over 802.11n. You can read more about Apple's preferred wireless roaming here: https://support.apple.com/en-us/HT206207

Good thought, although both the 3825 and 3935 are 802.11ac APs. I've heard from another vendor that they've experienced clients preferring the wave 2 AP over wave 1 APs in mixed setups.

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