How to renew a client DHCP address with an OpenWrt router, from its SSH terminal session?
Done the research and answering to the future me. OpenWrt uses
udhcpc as its DHCP client (rather than
dhclient). To renew DHCP leases on all interfaces, the following one-liner can be used (thanks to the source):
PID=`pidof udhcpc` && kill -SIGUSR1 $PID