mDNS discovery work on shell, but not in LaunchAgent

I've built a simple Python script that tries to discover my Sonos speakers via mDNS/UPnP/Bonjour and set some music sources to them. This is done using the [soco](https://soco.readthedocs.io/en/latest/getting_started.html) lib. The script works well when started on the shell. Starting it from a LaunchAgent (same machine, same user), it can't find the speakers.

import soco
from soco import discovery

found_speakers = discovery.discover(timeout=30)

Label
        sonos
        ProgramArguments
        
                /usr/local/bin/poetry
                run
                sonos-sanitizer
        
        RunAtLoad
        
        StandardErrorPath
        /var/log/sonos/sonos.stderr
        StandardOutPath
        /var/log/sonos/sonos.stdout
        StartCalendarInterval
        
                Hour
                5
                Minute
                35
        
        WorkingDirectory
        /Users/xxx/Code/sonos_sanitzer

I'm a bit puzzled as of why it doesn't seem to get network access when run via LaunchAgent. I've even extended the discovery timeout to 30 seconds. System is macOS 15 Sequoia. Caveat: The Mac is connected to multiple networks using VLANs.