Backup uplink not switching in due to stupid router splash screen

[Djsky123]

Ok, I have an MX64 with a primary uplink connected to a TalkTalk Business (UK) adsl router and the secondary uplink connected to a Three mobile 4G router.

Both work fine and failover if I unplug either cable.

However, there was an issue with the Broadband on the TalkTalk line where it had sync with the broadband line, but couldn’t actually see external sites. Therefore, whenever we browsed any site from inside the MX, we saw the default TalkTalk splash screen saying “your router needs configuring”.

Also, from the outside, meraki showed the appliance as unreachable.

it would not failover to the secondary uplink, even after two days!!!

I’ve looked at meraki’s criteria for the failover uplink to kick in, and I guess something else needs changing as this caused us an issue, and the fact the splash screen reports and responds to pings to any address, makes the MX assume it’s still connected correctly!

what can I do to sort this?

[Brash]

It sounds like the MX isn't failing over as one of the connectivity tests (most likely ARP for the gateway) is still available.

Is the MX receiving a public IP for it's WAN uplink, or a private IP behind the ADSL router?

[Djsky123]

Private IP behind the router, but in DMZ.

[Brash]

That makes sense why it would never fail the ARP test as your ADSL Modem/Router is still online.

You should be able to achieve the desired result by putting the ADSL router into bridge mode and connecting the MX to it. You may have to look at the specific way to configure it on your router but the end result should be that the MX receives the public IP address and acts as your gateway router.

Therefore when there's a failure anywhere upstream of the MX (whether it be the cable or the ADSL router in bridge mode), it should fail the ARP test and perform a failover to the secondary uplink.

[BlakeRichardson]

1. If you plug directly into the ADSL router bpyassing the MX can you access the internet.

2. Is the MX getting its IP via DHCP or is it manually assigned. 

3. Have DNS servers been configured.