How can I do this using AsusWRT?

[dwp]

I have some client IoT thermometer devices where the firmware has the DNS server to be used set to a fixed IP address (in this case 114.114.114.114). This is used to get the IP address of a web component (in this case SMARTSERVER.EMAXTIME.CN) to which data is sent (mostly using UDP).

I want to redirect at least the UDP to a machine on my LAN so I can eliminate reliance upon a possibly disappearing web component.

What is the best way to accomplish this? It seems like I need something at the LAN router level that can intercept the DNS requests made to 114.114.114.114 and return the IP of my choice. But I have no idea whatsoever how/if I can accomplish this.

BTW - I have a GS-AX3000 router.

So thanks for any advice/tips.

 

[dwp]

For some reason I cannot post the following. So here it is as an image. Sorry...

 

[ColinTaylor]

Stock Asus firmware doesn't support user scripts (although there are some hacks) so any changes will be lost when the router reboots.