[NEBULA] multiple APs using same channel in close proximity

HealthByRo

Why are multiple APs on the same controller using the same WiFi channels (2.4GHz and/or 5GHz) when they are physically in close proximity to each other?  Isn't DCS suppose to avoid this?   I can understand that this can happen on 2.4GHz but it really shouldn't happen on the 5GHz band since there are a lot more channels than I have APs in this location.

WebberIT

Did you happen to see the channels displaying the same set but in different seqences?
eg. 48*/36/40/44 vs 36*/40/44/48

HealthByRo

Example:  
40/36/44/48
and
48/44/36/40

But sometimes they are exactly the same.

Zyxel_Dean

Hi @HealthByRo
The different sequence @WebberIT is mentioning about is main channel or primary channel.The star character  ' * ' on one of the channels in the set, that means it is using that channel as primary channel and other ones are secondaries for building up the 80Mhz bandwidth.

DCS measures channel utilization and calculates the primary channel it's going to skip to, so it is likely to see same sets but different ones having * on it. In some occasions it could be the same if no other channel is better. 
The channels available to skip to is determined by the country code in which it's allowed and whether DFS should avoid.

Are there performance issues if the channels are the same? In my experience 5Ghz should be more capable of withstanding co-channel interference, it wouldn't be as dragging performance as 2.4Ghz. 

HealthByRo

Our throughput on the 5GHz channel has not surpassed 50Mbps, even with nobody else in the office and only 1 device on the AP.

WebberIT

That sounds like the channels are flooded with traffic, are you in a wifi dense area?
Try with different channels and check the linkspeed/datarate on your test kit before you start testing, it reflects the realtime speed of transmission. 

Zyxel_Dean

@HealthByRo
May I know on what channel and the RSSI of your client device(or how far the distance) was when you've performed the test? And if the SSID you're using is using captive portal?

There is a slight possibility that it was a performance bug, which is fixed in the latest patch. Suggested that you upgrade to the latest firmeware before trying out different combinations.