Xiaomi WiFi Router 3G (switch+wifi only configuration)

Hi guys,
I need to configure this device only for switch and wifi. (no need firewall,dhcp..)
I already have a main router and I want all devices in the same ip range assigned by the main router.
for example..

main router
xiaomi router
devices connected to the main router or xiaomi router - 192.168.1.x

In the end...I no need the wlan port of the xiaomi router
I just want a lan to lan connectiont and use the second lan port of the xiaomi for a wired devices.

How to proceed?
thanks in advance

  1. Give the lan interface on the xiaomi a static adress
  2. Disable the dhcp-server on the xiaomi lan interface.
  3. Maybe you can make a bridge between the lan-vlan and the wan-vlan and in that way have 3 lan-ports. I am not sure about that possibility.