Thanks. Do you mind if I add this to my post on the Amplifi discussion board? I don't know any of the Wi-Fi specs. It may be that the WSC spec doesn't take mesh into account, or it may be that they need to restrict their interchange to a single access point.

Bruce A. Johnson
Herndon, Virginia

On Wed, Nov 4, 2020, 16:54 Denis Kenzior <denkenz@gmail.com> wrote:
Hi Bruce,

On 11/4/20 3:29 PM, Bruce Johnson wrote:
> I received the error "Multiple sessions detected" from iwctl after running
> "iwctl wsc wlan0 push-button". The same Wi-Fi card was working with WSC on the
> same Wi-Fi router when I tried it a week or so ago, and I have since reformatted
> the disk of the computer with the Wi-Fi client station. After looking at the
> source of wsc.c, I believe I have bumped into something the code doesn't
> anticipate correctly in the case of a mesh Wi-Fi installation.

 From the log it looks like iwd is doing everything right...

>
> I was trying to pair a Qualcomm Atheros QCA986x/988x with an Amplifi HD Wi-Fi
> router that has an Amplifi mesh extender. Both units are running with SSID
> "topcog" on 2.4 GHz and 5 GHz, and they each have an additional SSID,
> "topcog_5ghz". It looks like iwd gave the pairing a thumbs-down because it was
> getting the same offer from two different BSSIDs for SSID "topcog" in the 5 GHz
> band. When I unplugged the extender and tried the pairing again, it succeeded.

According to WSC 2.0.7 (which seems to be the latest doc):
"During this scan, if the Enrollee discovers more than one Registrar in active
PBC mode then the Enrollee SHALL abort its connection attempt and signal a
“session overlap” error to the user."

"Note: In the case of a dual- band AP and a dual-band station, the station may
discover more than one Registrar in active PBC mode. If the dual-band station
does discover more than one Registrar in active PBC mode, one on each RF band,
and the UUID in the Beacon and Probe- Response are the same for all RF bands,
then the station shall not consider this to be a session overlap."

So looks like the spec doesn't explicitly allow wiggle room for the case you
encountered where both the AP and repeater with different BSSIDs are operating
on the same band and advertising a WSC session.

Regards,
-Denis