Openwrt downstream on a second router


I have a TP-Link sim card router that is connect through LAN with my second router downstream (WSM20) that is running openWrt. (WAN Port on WSM20 and LAN Port on TP-Link) So far so good but I am a complete newbie and have problems to set up the connection to them, the final goal would be to run SQM on the WSM20.

thank you in advance

this should work out of the box, just make sure the tp-link LAN subnet isn't the same as on the WSM20.

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When using typing in the browser, connections fails, by using I get connected with the SIM-card router, but not the WSM20 with openwrt on it. Did the installlation and sysupgrade by WinSCP and directly connecting my laptop with LAN to the WSM20

the subnets have to be different, you'll have to change the LAN IP of the WSM20.

The /24 in the end means a range of addresses, or "subnet". Since a web browser can't connect to a range of addresses, it thinks that you are trying to connect to server, and to path "24" in it. That will surely not work. Your WSM20 should have 2 ip addresses. The upstream address assigned to it by the sim card router, and a local address that WSM20 assigns to itself. The latter is the address that you should type in the web browser. And as frollic said, the upstream subnet and the local subnet should be different. In your case, the upstream subnet is something like On WSM20, you should set up a different subnet, for example And assign it an address like which belongs to that subnet.

Alternatively, if you can access your sim card router's management page, possibly you can set it up in bridge mode, so it acts like a modem and not like a router. In that case, WSM would act as a router. I personally have no experience with mobile internet modems, so I can't tell if this is feasible or not.

My current connection: SIM-router (LAN) --> OpenWrt-router (Wan)

The SIM-router lists the OpenWrt-router as "wired client" but I cannot access the OpenWrt-router anymore with my web-browser by typing the IP adress in the searchbar, this only still works for the SIM-router. Both routers are now on different subbnets.

Edit: Only when both routers are in the same subnet, I can access the OpenWrt router by connecting both routers through the LAN ports.

I have the same configuration: LTE-router(LAN) --- (WAN)OWRT-router(LAN) --- PC.
From the PC I can access OWRT-GUI as well as the LTE-GUI.

I guess, there is something in your OWRT config, that rejects or denies the access to your OWRT-GUI.

Thank you, so I know it definitely should work somehow for me too. I figured out I can only access the OWRT-router if both this and the LTE-router are on the same subnet and both are connect through their LAN-ports.

I am still a newbie regarding OpenWrt, so I just want first to connect the OWRT-router wirelessly to the LTE router by joining the existing Wifi-network hosted by the LTE-router. Can I do this while being on the same subnet?

From my understanding when using the OWRT-router as client, I can do that either wired by using the setup mentioned by @Barney (this should work out of the box) or by joining an existing wifi-network from the LTE-router.

It's not clear for me, how you want to connect your devices. Can you give us a little diagram?

Sure! I actually found this diagram from another user here on the forum which applies to my situation too:

Only differences here are:

1.I connected the "internet-router" and the "openwrt-router" both through their LAN-ports and not using the WAN-port on the openwrt-router (which is the case on the diagram above)

  1. the internet-router gets it internet connection from a SIM-card.

Both routers are on the same subnet, I configured the openwrt-router as an AP and everything works fine now, but I am just not sure if it is safe and okay to use the LAN-port instead the WAN-port in this configuration.

So, is your problem now solved?

Of course it's safe. But the question is: what is your goal, what do you want to achieve?

You can operate a router in AP mode or in router mode. It depends on your needs. Both modes are safe and fully supported by OpenWrt.

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Yes I was able to solve it.
For now I am happy to operate the router as an AP