Script to reset WAN interface

Hello Guys.
Need a litle help here.

I'm using OpenWRT on a Xiaomi router 3G to replace my ISP's router.
I finally was able to make everything work since I have an optical conection with IPTV on single edge, but I'm running into a problem, everyhing works great including the multicast traffic. But when I restart the router my ISP is giving me the same address to the IPTV interface and WAN interface, but when I reset the WAN interface I receive an public IP and everything works ok.

I'm a noob regarding shell scripts, can anyone make me a script to reset the wan interface after 1 minute of the roter boot, no more resets are required, only on boot. The interface's name is simply WAN.

Thanks guys.

You can try to run ifup wan after a reboot and check if it works for you.
If it does, add it in /etc/rc.local before exit 0.