Telia Sagemcom and 1.1.1.1

If you are unfortunate enough to have been given a Telia WiFi router model F@st 5370e made by Sagemcom, you may have experienced that IP 1.1.1.1 is unreachable. [1, 2, 3]

1.1.1.1 is a public DNS server provided by Cloudflare that many of us prefer to use, instead of, let’s say, Telia’s own snooping DNSes of Google’s 8.8.8.8. Of course, an alternative is to use 1.0.0.1, which also provides the same service by Cloudflare, but where is your backup DNS in that case?

The reason it is unreachable is that the router is using this IP internally for an interface called “IP_BR_LAN_LXC“. LXC is a userspace interface that can be used to create and manage application containers.

You can disable the “IP_BR_LAN_LXC” interface by following the instructions given below:

  1. Login to you router’s “admin” (sic) interface by browsing to http://192.168.1.1
  2. If you’re using Firefox or Chrome, press “F12” and navigate to the “Console” tab.
  3. Enter the following command and press Enter: $.xmo.setValuesTree(false,"Device/IP/Interfaces/Interface[Alias='IP_BR_LAN']/IPv4Addresses/IPv4Address[Alias='IP_BR_LAN_LXC']/Enable");

That’s it, 1.1.1.1 should now be reachable. I have not experienced any issues by disabling this interface. Maybe I’ve blocked Telia from using some remote tools to mess with my router? I call this a win in that case. If for some reason, you want to reverse the setting above and re-enable this interface, you can do so by typing the following command into the console:

$.xmo.setValuesTree(true,"Device/IP/Interfaces/Interface[Alias='IP_BR_LAN']/IPv4Addresses/IPv4Address[Alias='IP_BR_LAN_LXC']/Enable");

Bonus: While you’re at it, block 8.8.8.8 and 8.8.4.4 from your network. Reason? Android, and in general Google devices, are using this DNS regardless of your DHCP settings. You can block them by going to this hidden path in your router and adding 8.8.8.8 and 8.8.4.4:

http://192.168.1.1/0.1/gui/#/access-control/parental-control/filtering

PS: You can either change the DNS servers on a per-device basis, or you can change the DNS servers that your DHCP server is announcing to your local network. This can be done using the following hidden URL:

http://192.168.1.1/0.1/gui/#/mybox/dns/server

DISCLAIMER: I don’t take any responsibility for any of your actions blah blah blah…