Hi Keith, On 10/14/20 6:52 PM, KeithG wrote: > I have been struggling with this problem for a while and *think* I have narrowed > it down to an Arch Linux problem. My main focus is to get iwd/connman to work on > my RPis as iwd connects so much faster when it works. Current versions on Arch > Linux are Connman = 1.38 and iwd = 1.9. The kernel I'm running is 5.4.70. > > It does not behave absolutely consistently but there are themes. If I have > connman managing the connections, when the SSID goes away, iwd stops scanning. > This is very consistent. It does it first time every time. SSID goes down, it > disconnects and sits there. On Arch Linux, it does not seem to be dependent on > card (broadcom/intel) or hardware (x86_64,armv6/armv7/aarch64). iwd quits > scanning when the SSID goes away. The monitor-iwd script shows 'Scanning = > False' and it never rescans. Connman invokes Station.Disconnect() which tells iwd to also not enter into its own Autoconnect phase. I think the idea is for ConnMan to scan periodically, but I guess it doesn't do this for whatever reason. > When I use systemd-networkd with iwd, I get better behavior, but it can also get > to a point where it quits scanning. This happens after a few times of turning > off then on the AP on the router. When it quits scanning, monitor-iwd says > "Scanning = False" and it never rescans. The last time I ran it, the monitor-iwd > script says Scanning = True then immediately Scanning = False but nothing was > scanned. It did this 13 times but never 'saw' anything nor connected. If I down > then up the interface (ifconfig wlan0 down; ifconfig wlan0 up), it immediately > connects. I now have a script that runs when the interface goes down to do this > (down/up), but shouldn't iwd eventually reconnect? We would need to see iwd debug logs and iwmon logs to say much more... https://iwd.wiki.kernel.org/debugging > > This contrasts with the same computer running RasPiOS. It is running the same > kernel and the same broadcom firmware (I updated both to be identical) connman > is 1.36 and iwd is 0.14, but it works every time all the time. I cannot get it > to not reconnect. In fact it connects faster than the web page for the router > registers it. > > I built iwd 0.14 and connman 1.36 for the Arch install and it behaves the same > as iwd 1.9 or the iwd git master build. It just quits. > > What underlying OS issues could cause this? I have built the kernel with the > same config options for both installations with the same computer doing the > building. Both installations are using the same kernel, firmware and driver > version (built with the kernel). > Hard to say without logs... Regards, -Denis

As I've said before, connman is invoking Station.Disconnect which prevents iwd from reconnecting autonomously. There's really nothing we can do about that. Any issues are likely in connman.git/plugins/iwd.c

So iwd is built to scan the least amount possible, since scanning interrupts your link (radio has to physically switch off the channel, so your packets are lost in the meantime). We scan only when in 'Autoconnect' state and when signal strength gets so low we need to try and roam. If the network supports neighbor reports or other advanced BSS mangement features, we use those to minimize the set of channels we scan.

In Autoconnect mode (and only in Autoconnect mode when we're not connected anywhere else) iwd scans periodically. If a network is marked AutoConnect=false, then that network is not considered as a candidate in this stage. Station.Disconnect tells iwd to disconnect from whatever it is connected to and not enter into its Autoconnect mode. This is essentially used to tell iwd that some external application wants to control how scanning & autoconnect logic is performed. In general, I would encourage using iwd's autoconnect logic since it can optimize the scan parameters and reconnect quickly. This is why you see iwd re-connect to networks about 10x faster than NM+wpa_s.