Remove DHCP Leases
https://forum.archive.openwrt.org/viewtopic.php?id=63400
remove ip leases without rebooting router
stop interface or power off device to release old ip
remove lines from openwrt /tmp/dhcp.leases
make sure static lease reservation ip and mac addresses are correct
from luci: system > startup > dnsmasq > restart
start interface or power on device to get new ip