The SignalLevelAgent API is currently broken by the system bus's
security policy, which blocks iwd's outgoing method call messages. This
patch punches a hole for method calls on the
net.connman.iwd.SignalLevelAgent interface.
There is no need to punch the holes for netdev/wheel groups to send to
the .Agent interface. This is only done by the iwd daemon itself and
the policy for user 'root' already takes care of this.
The 'at_console' D-Bus policy setting has been deprecated for more then
10 years and could be ignored at any time in the future. Moreover, while
the intend was to allow locally logged on users to interact with iwd, it
didn't actually do that.
More info at https://www.spinics.net/lists/linux-bluetooth/msg75267.html
and https://gitlab.freedesktop.org/dbus/dbus/-/issues/52
Therefor remove the 'at_console' setting block.
On Debian (based) systems, there is a standard defined group which is
allowed to manage network interfaces, and that is the 'netdev' group.
So add a D-Bus setting block to grant the 'netdev' group that access.
