Backup Cell Phone / WIFI Hotspot "Bridge" over dedicated Interface to use a secondary WAN on a downstream router

So im using a Netgear WNDR3700v5 running OpenWrt 18.06.4 r7808-ef686b7292 / LuCI openwrt-18.06 branch (git-19.170.32094-4d6d8bc)

I dumbed it down and turned off DHCP, VLAN'd each wired port, left one port for LAN and set that to a static IP on my current LAN ( trying to use that as a management interface of sorts.

What i would like to do is run this as a dedicated WIFI bridge that i can use to connect to a Cell based hotspot and bridge a wired connection over to the secondary link of an Opensense box.

I have this devices working to some degree as follows:

WIFI connection to my phone for testing the cell handoff (Big11MaxPro)

relayd to create a relay bridge for passing DHCP over (Cell_Relay)

one vlan'd port for handoff (Cell_BackUp)(Port3)


I can connect my laptop to port 3, get an IP from my phone in the 172 range and connect to the internet. Open WRT external IP and i can access the device over the LAN interface.

Semi Works:

If try to connect to the WAN port on my Opensense box, it seems to also grab a 172 address BUT this is where things get strange:

Via console and monitor i can see the box get the IP BUT if i try to ping anything on the internet, NO DICE

IF i connect my laptop to the LAN port of the Opensense box, i get a NATTED ip (as expected) but also NO internet.

I feel like im missing something or because of how im trying to the the device in more of a transparent mode and NOT as my actual WAN and LAN router its not configured correctly.

i loosely followed this wiki for relayed but where it asks to change to the WWLAN (Big11MaxPro) interface to Static, that breaks the entire set up and i can no longer access the OpenWrt box BUT it still seems to be connected to my phones hotspot.

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A standard AP-STA link cannot be bridged. The STA must be in its own network. Then you can route other networks to it. This is simplest to set up by starting with a default configuration, remove the Ethernet port from the wan network, and configure a STA that links to the phone and uses wan as its network. This is also how you would use any AP that you don't control, such as a hotel, as the link to the Internet.

A cell phone USB tether can be bridged. But the phone will do all routing and firewalling then, OpenWrt has no control of it.


Sorry sounds helpful but im missing something.

When you say its own network, can you elaborate?

A cell phone USB tether can be bridged. But the phone will do all routing and firewalling then, OpenWrt has no control of it.

Right now i seem to be getting this to work without the USB which to your point is not how i want it to work.

Like i had found this thread and is what i kinda started with:

But you mean more like this:

I.E. You cannot bridge it to another interface - as described:

Sorry not tryint o be difficult just routing isnt my strong suit.

so for example my current network is

in Open WRT for the Cell interface that is made via the gui, i need to set the IP of that device to static and that IP needs to be OUTSIDE of my network range?

ie something like

Then i have to make some sort of a FW rule that routes traffic from my LAN to this new WAN via this new network?

I recall reading something like this in the relayed instructions and it was confusing

Also to be clear, i used "bridge" as a loose term, i just want to to work even if bridging isnt the correct term or way to make it work.

I would be very happy if i could just use this device to connect a Cell or public wifi to my Opensense as a "secondary or backup link"

Just place it in the same WAN firewall zone.

  • Isn't this an email server?
  • To be clear, you want 2 Internet connections on an email server?

(If so, I hope you also know how to setup after having 2 gateways. If you need info on that as well - that won't be OpenWrt-related.)

Never mentioned anything about an email server sorry not sure where that came from.

Just place it in the same WAN firewall zone.
Right now i have the original LAN zone dumbed down to only one port (lan-br) and set to static address on my own lan (
That port just has to reside in the WAN zone? Or do i place "another" port into that WAN zone?

As for opensense, yes that another problem, so here i just need to get this device working as transparently as possible to "bridge my cell via ethernet" via this device.

As per the attached, br-lan is port 1 on the router and i was "trying" to have port 3 server as the handoff for the cell to the "downstream router"

What is opensense?

WiFi or Wired?

  • Again, you cannot bridge WiFi (I understand this is just a terminology miscommunication here)
  • And you provided the links for connection information for WiFi

So what issues are you having?

Opensense is another open sourer router software that you run on x86 hardware.

So once this device is working well as a cell or wifi handoff, that device will do my actual LAN routing.

This device only has to work as bridge between a Cell or wifi connection to a lan port

i hope this make sense


Scan, join network - do not replace config.

  • And what happens when you proceed?
  • What issues are you having following the instructions

(At this time, I don't understand what issue(s) you're having.)

So as stated from the start, i can connect to my cell phones hot spot.

I can get an IP from it an get internet access while using the OpenWRT device.

BUT i DONT want to use this device as my MAIN router

I want this device to take that connection, and pass it down to another router

THAT IS where im starting to run into trouble.

In a perfect world, that hand off is done via a specific port so that i can still have access to the device via another port that is still on its "LAN"


What device?

  • The cell?
  • The OpenWrt?

Then simply connect the cell to the device you want to be your router.

Can you better explain what you mean by this? *

  • Do you mean connect to the cell via wired?
  • If so, do you need link to instructions?

*- It seems like you're still asking how to WiFi bridge - then saying you're using the wrong term; but it seems you in fact you do wish to bridge...?

It's been noted you cannot do that, so perhaps I'm just misunderstanding.

EDIT: To be clear- it seems you wanna

Cell <-WiFi-> OpenWrt <-BRIDGE_Network-> Opensense <-> clients

So the opensense gets it's IP directly from the cell, correct?

Cell <-WiFi-> OpenWrt <-BRIDGE_Network-> Opensense <-> clients

Correct, Opensense should get one IP from the cell connection

it would then NAT that IP as it would any other WAN connection.

I was able to make some progress and using relayd i am able to connect to BOTH my cel phone and public wifi hotspot AND bridge that connection over to my Opensense box BUT i loose access to OpenWRT gui even thought its still up and running.

Relayd would be my last choice. Double-NAT generally isn't an issue on a backup connection. Today's IPv4 going through a cell phone company is usually subjected to several stages of NAT and 464 anyway.

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Why would relayed be your last choice? I ask as that seems to be the only way this works, and most of my searching keep pointing me towards that answer?

Ive made more progress and now can get my cell connected and still have access to the OpenWRT.

As of right now it seems to be working as expected....

Since you say relay and bridge together, it's confusing.

I think what you're saying is that by relayd, somehow you got the cell to issue an IP to the opensense.

OK...but since the OpenWrt's connection cannot be bridged, you are not on the same network as your cell's gateway (and that is an issue).

Yes, it's not longer in that IP subnet - you got an IP from your cell. That will be difficult to resolve, save setting up a separate management VLAN to plug into when needed.

So it's all working now (Internet from cell, other WAN and access to OpenWrt)?

You seem to be making progress, so, cool! :+1: