Hello,

I try to get iwd running on a Raspberry Pi using a Raspbian kernel (5.4.59). 
The needed kernel options should be added (https://github.com/raspberrypi/
linux/issues/3547), wpa_supplicant works, I compiled a kernel adding 
CONFIG_KEY_DH_OPERATIONS (which was the only remaining complaint by iwd), 
upgraded to iwd 1.8 but had no success.

Now I am running out of ideas what else to try. The (hopefully) relevant part 
of iwd running in debug mode for 2.4 GHz:
> src/station.c:station_autoconnect_next() Considering autoconnecting to BSS
>     '98:9b:cb:4b:b1:cc' with SSID: auenstein, freq: 2472, rank: 7090,
>     strength:  -5600
> src/station.c:station_enter_state() Old State: autoconnect_quick, new
>     state: connecting
> src/station.c:station_netdev_event() Associating
> src/netdev.c:netdev_unicast_notify() Unicast notification 59
> src/netdev.c:netdev_mlme_notify() MLME notification Connect(46)
> src/netdev.c:netdev_connect_event()
> src/netdev.c:netdev_link_notify() event 16 on ifindex 3
> src/netdev.c:netdev_link_notify() event 16 on ifindex 3
> src/netdev.c:netdev_link_notify() event 16 on ifindex 3
> src/netdev.c:netdev_link_notify() event 16 on ifindex 3
> src/wiphy.c:wiphy_reg_notify() Notification of command Reg Change(36)
> src/wiphy.c:wiphy_update_reg_domain() New reg domain country code for
>     (global) is DE
> 4-Way handshake failed for ifindex: 3, reason: 15
> src/station.c:station_connect_cb() 3, result: 3
> src/station.c:station_disassociated() 3
> src/station.c:station_enter_state() Old State: connecting, new state:
>     disconnected 

And the same for 5.6 GHz with a different error:
> src/station.c:station_autoconnect_next() Considering autoconnecting to BSS
>     '98:9b:cb:4b:b1:cd' with SSID: auenstein5G, freq: 5600, rank: 4592,
>     strength: -6500
> src/station.c:station_enter_state() Old State:
>     autoconnect_quick, new state: connecting
> src/station.c:station_netdev_event() Associating
> src/netdev.c:netdev_unicast_notify() Unicast notification 59
> src/netdev.c:netdev_mlme_notify() MLME notification Connect(46)
> src/netdev.c:netdev_connect_event()
> src/netdev.c:netdev_link_notify() event 16 on ifindex 3
> src/netdev.c:netdev_link_notify() event 16 on ifindex 3
> src/netdev.c:netdev_link_notify() event 16 on ifindex 3
> src/netdev.c:netdev_link_notify() event 16 on ifindex 3
> src/wiphy.c:wiphy_reg_notify() Notification of command Reg Change(36)
> src/wiphy.c:wiphy_update_reg_domain() New reg domain country code for
>     (global) is DE
> src/netdev.c:netdev_link_notify() event 16 on ifindex 3
> src/netdev.c:netdev_mlme_notify() MLME notification Disconnect(48)
> src/netdev.c:netdev_disconnect_event()
> Received Deauthentication event, reason: 2, from_ap: false
> src/station.c:station_disconnect_event() 3
> src/station.c:station_disassociated() 3
> src/station.c:station_enter_state() Old State: connecting, new state:
> disconnected 

I could imagine, that there is still a kernel module missing, but this is just 
guessing. Any hints how to continue debugging?

I still think that iwd would be a good match for the Raspberry Pi and ideally 
after this issue is fixed most Raspberry Pi user can switch to iwd if they 
like.

Kind regards
Patrick