Raspberry Pi Forums

Hi all,

I have a small setup with 4 RPI3 B+.
I want to do some ad-hoc tests. In order to avoid interferences, I want to use two different channels.
To do so, I connected PI1 and PI2 through wifi with frequency 5.745 GHz. The other pair (PI3 and PI4) uses a different frequency which is 5.805GHz.
P1 and P3 are connected through ethernet.

I used BATMAN-ADV to easily set the whole thing up. So far so good, each PIs are reachable.
I then wanted to do some bandwidth tests using iperf3:
- PI2 as server and PI1 as client => I get an average 20 Mbps
- Same thing withP4 as server and PI3 as client

However, when I trigger the iperf3 tests between PI1/PI2 and PI3:PI4 in parallel, things are getting messy!! Indeed, the bandwidth drops up to less than 1Mbps on both PI pairs

I checked that there are no other access points using channels close to those I picked so this cannot come from my environment.
The channels I use are 20Mhz wide according to "iw wlan0 info" results so the should not overlap with each other.

To my understanding, I should not get any interferences between the two channels right? Or am I missing something obvious?

I actually found my issue.
I had some ACI (Adjacent Channel Interferences) since the RPIs were very close.
Reducing the TX power to 1dBm fixed my issue.
Hope this can help someone else.