Multicast discovery not working when wireguard device present

Cheers, ran into a rather weird issue just now. Starting mkchromecast as normal (both versions in AUR, doesn’t matter):

Mkchromecast v0.3.9
Creating Pulseaudio Sink...
Open Pavucontrol and Select the Mkchromecast Sink.
Starting Local Streaming Server
[Done]
Selected backend: parec
Selected audio codec: mp3
Default bitrate used: 192k
Default sample rate used: 44100Hz.
PID of main process: 284407
PID of streaming process: 284414
 * Serving Flask app 'mkchromecast.audio' (lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
 * Running on http://192.168.178.11:5000/ (Press CTRL+C to quit)
Traceback (most recent call last):
  File "/usr/lib/python3.9/site-packages/soco/discovery.py", line 212, in any_soco
    d for d in cls._instances[cls._class_group].values() if d.is_visible
KeyError: 'SoCo'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/bin/mkchromecast", line 311, in <module>
    mk()
  File "/usr/bin/mkchromecast", line 59, in __init__
    self.audio_linux()
  File "/usr/bin/mkchromecast", line 78, in audio_linux
    self.cc.initialize_cast()
  File "/usr/share/mkchromecast/mkchromecast/cast.py", line 118, in initialize_cast
    zone = soco.discovery.any_soco()
  File "/usr/lib/python3.9/site-packages/soco/discovery.py", line 215, in any_soco
    devices = discover(allow_network_scan=allow_network_scan, **network_scan_kwargs)
  File "/usr/lib/python3.9/site-packages/soco/discovery.py", line 124, in discover
    _sock.sendto(really_utf8(PLAYER_SEARCH), (MCAST_GRP, MCAST_PORT))
OSError: [Errno 126] Required key not available

So I’m guessing it’s an issue with my network interface, as it’s sitting on a bond interface and probably has some deeper issues trying to do multicast there. Since other apps (e.g. noson) appear to have no problem finding the SONOS device, I’m guessing it’s something to either be fixed in soco… or Python. (welp.)

FWIW, the networki device for 192.168.178.0/24 is just a simple bond device with

[NetDev]
Name=xxxx
Kind=bond

[Bond]
Mode=active-backup
MIIMonitorSec=1

Debugging hints greatly appreciated, a quick googly-go didn’t reveal anything too obvious to try with regard to multicast with python on bond devices.

[pwt]

SoCo v0.24.1 is now released, which should address this issue. Please re-open if this is not the case.

[towo]

Sounds great. 👍

Was just now looking into how to check the device capabilities to have this be less trial and error, but didn’t find anything that looked portable enough.