I get this message spawned every 10 seconds on all terminals.

Development UX
1

multicastBeacon: Failed service 'Service@0xc00014ebc0 created by multicastBeacon@0xc0002025a0/writer' (2.012610 failures of 2.000000), restarting: false, error: write udp [::]:36056->[ff12::8384]:21027: sendmsg: cannot assign requested address

why is a lapalie treated so aggressively?

This is not the first time I see aggressiveness here.

It is understandable that people want to disable UDP and tcp6. Spamming them with aggressive kernel messages is not OK.

2

You can disable ipv6 if you want, but then maybe disable the corresponding addresses in Syncthing. I don’t know why they would end up on all terminals, we print errors to stdout.