Dhcp Setting

Hello Guys

I have router Beryl Gl-MT1300, i want to set up Dhcp conectivity MTU setting on 1500, where i will find this setting?
Here is a link of a video what I am trying to do.

I don’t know if it works, but pls try this:

First install Luci, then go to network->interfaces->Lan

Then in the bottom part, pls add the mtu option as in the image