If you're logged in on the pi, you can modify the file below, change the broadcast ip value to match your network assuming you have dhcp enabled on your router or just update the values in the file.
cat /etc/config/network
config interface 'loopback'
option ifname 'lo'
option proto 'static'
option ipaddr '127.0.0.1'
option netmask '255.0.0.0'
config interface 'lan'
option ifname 'eth0'
option type 'bridge'
option broadcast '192.168.100.255'
option proto 'dhcp'