This guide provides an easy configuration to access the web-based UI of your xDSL/Cable modem connected to the WAN port of your Asus router. Important! - This only works if you are able to access the modem's configuration (some ISPs have restrictions on their equipment). For this to work and to avoid issues, your modem and router will be configured to utilize different subnets.

1. Change your modem's LAN IP address to 192.168.0.1. Here's an example from a TP-Link ADSL modem:

   

2. Go to LAN -> LAN IP. Ensure your router's LAN is on a different subnet; by default it will be (the default IP address is 192.168.1.1). Click Apply.

   

3. Test if you can access the modem's interface. Open your browser and enter http://192.168.0.1

   

4. If the above step fails, go to WAN -> Internet Connection -> WAN IP Setting (section). Assign your router an IP from the modem's subnet by applying the following settings:

   WAN IP Setting
   Get the WAN IP automatically	⚪️ Yes 🔘 No
   IP Address	192.168.0.2
   Subnet Mask	255.255.255.0
   Default Gateway	192.168.0.1

   and click Apply at the bottom.

   

   

   Then retry step (3) above.

That's it !

Alternative

If the above does not work, you can assign a virtual interface to eth0 - the WAN port. Keep your WAN config to "Automatic IP" then SSH into your merlin router, and use this command:

ifconfig eth0:1 192.168.0.2 netmask 255.255.255.0

What this does is you assign a virtual interface to modem subnet 192.168.0.1 used in the example above. For the majority of us, it might be 192.168.1.1 Do check before you assign the interface. After assigning, go to 192.168.0.1 (your modem webui page) to test.

Do note the command does not persist after reboot.

To make it persist, go to jffs/scripts, modify init-start to include the above ifconfig command.