Use SSH to log in to the openwrt backend;
the default web server used in openwrt is uhttpd,
enter the configuration file path:
cd /etc/config/
Use the vim editor to modify the uhttpd file
vi uhttpd
Modify the port behind the red part above
Open the uhttpd file in the vim editor.
After the modification is completed, click ESC on the keyboard to exit the editing state, and then enter: wq to save the edit.
After saving, enter the command to restart uhttpd (or restart the router)
root@OpenWrt:/# /etc/init.d/uhttpd restart (restart # reboot)
Use the new port to log in to the web client and you are done.