vim /etc/config/system
config system
...
option log_ip <destination IP>
option log_port <destination port>
option log_proto <tcp or udp>
config rule option target 'ACCEPT' option dest 'lan' option proto 'tcp udp' option dest_port '5555' option name 'ACCEPT-LOG-DEVICE-LAN'
https://openwrt.org/docs/guide-user/base-system/log.essentials