In OpenWRT interface updates are registered through PROCD but it is not working in TOS
and the developers cannot be bothered since months however
It needs a hotplug script instead, perhaps until some unknown date TOS 4.x might be released (if ever).
For a hotplug script you may find some inspiration from one located in /etc/hotplug.d/iface/, something like
if [ "$ACTION" != "ifup" ] && [ "$ACTION" !=