What is my modems IP?

So my cable modem is connected to the Sophos XG firewall that acts as the router. I use 192.168.168.x for my internal network and .1 is my router/XG. What is the IP for my cable modem? Is there an easy way to find this? I assume I would have to create a firewall rule to access the web admin page of my modem but first I need to find its IP. Confused!!

  • This could explain some of your irobot issues. The modem should be in bridge mode so it will not have an IP address.


  • Your cable modem IP should be listed here:
    Configure -> WAN Link Manager -> IPv4 Gateway -> IP Address

    It will likely be on a different subnet.  To access it from your network you'll need to add an alias for your WAN port that is the same subnet as your modem.  You can do that here:
    Configure -> Interfaces -> Add Interface -> Add Alias "select the external WAN port"

  • In reply to rfcat_vk:

    Ian - really? I thought we would do this via firewall rules. So I have 4 ports. I just set up the firewall rule to allow traffic and everything works (except for the robot). Am I missing something? The modem is just a modem - not a router - just FYI. Is there like best practices guide so I get this right. I really should read some manuals I guess. 

  • In reply to Casual_User:

    I can't seem to get this to work. Like the OP, I have a cable modem connected to my Sophos XG box (4 port Qotom device). When I check under 'Network' -> 'WAN link manager', it shows the cable modem with an IP address of, with the Interface IP address being my external IP address which also starts with (IP address are not my actual IP addresses but hopefully explains what I'm seeing).

    My LAN address is 172.16.16.X.

    If I connect directly to my cable modem, I can access the web interface using

    I've tried adding an alias as described on my WAN port, but still unable to access it. I've tried both, and

    I guess I'm still confused what the local IP address is for my cable modem attached to my WAN port (the 69.XXX.XXX.X isn't a LAN address, so I'm assuming that's probably my ISPs gateway address?).

  • In reply to shred:

    Well, I tried accessing my Motorola Surfboard cable modem again this morning on and it worked. I did not have to setup any alias. Not sure what changed but I had no luck yesterday. So for anyone with the same modem and setup, it appears you don’t need to create an alias to access the modem web UI. Just try again on a different day I guess.... makes no sense.

  • In reply to shred:

    Now I can no longer access it. Getting the Sophos “Website not available” page. I made no changes or updates to my firewall. Any ideas?

    Edit: Restarted Sophos XG and now I can access it... not sure what the issue is.