This article provides information on which settings to check when you are not receiving syslog messages from all interfaces.
All Kiwi Syslog version
By default, the UDP socket will listen for messages on all connected interfaces. If you want to limit the binding to a single specific interface, you can specify the IP address in the Bind to address field. Otherwise, leave this field blank. If the Bind to address field is left blank, it will listen on all interfaces. This is the best option in most cases.
For example, if you have two non routed interfaces on the computer, 192.168.1.1 and 192.168.2.1, then you can choose to bind to only the 192.168.1.1 interface. This will ignore any syslog messages sent to the other interface.