Back to basics

It's probably six years since I first installed OpenWrt on a device. I don't really understand much about routing, especially the terminology, but after a few days struggling I manage get a particular device working and the leave it alone for a year or two without issue. Now I'm struggling to get my TP-LINK WDR3600 configured after upgrading it to 21.02.1 ...

I connect a cable from a LAN port on the device to my PC. I login to LUCI using without a problem.

What I want to do is change the device's static IP address so that I can login to LUCI from the PC using, but at the same time access the Internet which has a gateway address of The device is connected to the gateway via the WAN port.

Can someone tell me in simple terms what changes I need to make through LUCI to achieve this?

Thanks in advance.

If your device have the IP .1.5, and your gw is .1.1, you cannot use the WAN port, since the openwrt LAN side will use the same subnet as the WAN side.

If what you are saying is there allready is a firewall/router on the network .

other firewall router > openwrt wan port > local lan computer to openwrt lan ports

then all you need to do is change the ip of the lan interface on openwrt .
and under Networking > firewall turn off masquerade for wan interface .
Double NAT works but is problematic so better turn it off.
even worse is that it is same subnet :slight_smile:

under network> staic routes
and add static route for subnet interface wan
and add staic route for subnet interface lan

that is all

openwrt will still act as secondary firewall but without masquerading
as the other devices is handling that.
openwrts default gateway will be 1.1
default gateway for lan computers connected to lan will be 1.5

But better yet , just change the lans subnet to be sometheing else , and keep masquerade off
but first router will then need a static route to new lan subnet on openwrt , openwrts wan interface ip being the gateway for it.
if masquerade is on there is no need for that static route (but then there is double NAT to get on the internet = bad)