The 3.4.3 upgrade caused an issue where syslog data sent in UDP did not get processed correctly. A fix will be included in the next release, but to fix this manually, follow these steps.
Edit the syslog-ng startup configuration file:
sudo nano /etc/systemd/system/syslogng.service
Scroll down to where it says:
--publish 0.0.0.0:514:514 \
--publish 0.0.0.0:5514:5514 \
Replace those two lines with the following four:
--publish 0.0.0.0:514:514/tcp \
--publish 0.0.0.0:5514:5514/tcp \
--publish 0.0.0.0:514:514/udp \
--publish 0.0.0.0:5514:5514/udp \
Save the file by typing ctrl+x, y, enter.
Finally, activate the new configuration:
sudo systemctl daemon-reload
sudo systemctl restart syslogng
Please reach out to support if you need any assistant in this matter.