Setting up Internet failover on UDM Pro, with Teltonika RUT241

2023-04-21 18:37:00

It's no secret that I use Ubiquiti equipment for my networking. My office runs on a UDM Pro, which has been great for me. 

The UDM Pro performs well and stable, it has a great feature set and it's easy to manage (for someone who wants to spend little time managing their network). Heck, even site-to-site VPN for my security cameras was simple!

My main WAN connection comes from MAC3Park, my housing company. They recently had an outage on my Internet connection, which lasted a few days. That messes with my backups and a few of my business processes, so I want to have at least some form of alternative in place. 

Luckily, the UDM Pro also makes it dead simple to configure automatic failover or even load balancing across two WAN connections! It really is amazingly simple! Or it should be, as we'll see in a bit. 

As a second Internet connection, I looked into getting 4G/5G from my mobile provider. Ubiquiti have their own LTE/4G/5G solution, which looks awesome but is a bit expensive. For half the price, I got a Teltonika RUT241 aimed at IoT solutions.

Sure, the LAN port on the RUT241 is slower (10/100Mbit), but seeing how the 4G connection averages around 20MBit that'll be fine. That's also where the "should be simple" I mentioned earlier comes in. 

The RUT241 worked great with my laptop, but hooking it up to the SFP RJ45-module on the UDM Pro it just wouldn't go. No amount of changing settings would make it work. Very odd! There was no DHCP lease and even a statically assigned IP wouldn't let me connect to the Teltonika.

Turns out that, upon closer inspection, my vendor sent me the wrong SFP module :) I'd ordered the 1G model (which does 10/100/1000), but they sent me the 2.5G (which does 1000/2500/10000). The latter will not work with the Teltonika. 

Time to get that SFP replaced by my vendor and we'll be good to go!

EDIT:

Or even better! I could just switch my cabled connection from MAC3Park (which is 1G) to port 10 and switch the Teltonika to port 9 (which natively does 100/1000). So basically, switch the definitions of WAN1 and WAN2 around!

EDIT2:

That worked. 

I made port 9 WAN2 and port 10 WAN1. I switched the cables around and now port 9 happily runs at 100Mbit, connected to the Teltonika.

Even nicer: in bridge mode, port 9 gets the 4G IP address so it's perfectly accessible as intended. But in that same bridge mode, the RUT241 remains accessible on its static, private IP as well so you can still access the admin web interface. 

So if, for example, my internal LANs are 10.0.10.0/24 and the Teltonik's private IP is 10.0.200.1, I've setup a traffic management route which says that 10.0.200.0/24 is accessible via WAN2. That way I can manage the Teltonika web interface, from inside my office LAN, even when it's in bridge mode. Excellent!

EDIT3:

I tested the setup! 

Setting the UDM Pro to failover between the connections works very well. Within 60 seconds, Internet-connectivity was restored. It does seem that the dynamic DNS setup does not quickly switch over, so a site-to-site VPN will fail for a lot longer.

Setting the UDM Pro to load balancing didn't work so well. The connection remained down after I pulled WAN1.


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