How to easily set up a redundant internet connection

When our DLS connection failed a couple of weeks ago, it became clear to me that we needed a backup of some sort. I looked into business DSL subscriptions, but if you need a fast guaranteed repair time, the monthly rates start to look like mortgage payments. That’s why I decided to get a second consumer broadband line and hook try to somehow tie them together into one, easy to use local network. Thanks to a great router by Draytek and some clever tips from various forums, this turned out not to be very difficult at all. Here’s what I did.

Dual WAN setup

First, get a second line

coax connectorMy primary connection is a DSL line, so I decided to get cable as a backup. A single telephone line can only be used by one provider at the same time, so I wouldn’t be able to get another DSL connection. But a more important reason is that even if you have two telephone lines, any failure in your local telephony network will probably still knock out both. By going for a completely separate infrastructure, I hope to avoid this.

Another option is to get a 3G USB modem. The Draytek router can use most of those as the backup connection, but since portability is not an issue for my home network I decided to go for a speedier cable backup.

You’ll need a Dual WAN router

Draytek 2910G Dual WAN routerDual WAN (or multi-WAN) is tech speak for a router that can juggle more than one ‘incoming’ internet connection. Most routers have a single WAN port, which you hook up to your modem. These have two or more. It may sound complicated, but it really isn’t. There are other brands that offer Dual WAN routers, but here in The Netherlands, Draytek seems to be the only consumer brand that offers this type of product.

Dual-WAN router do not come cheap (mine was around 200 euro), but since they let you use the second connection instead of paying for a line you’ll only use in cases of emergencies it seemed like a good investment to me. To cut costs a little, I went for the wireless-g model, but there’s a wireless-n one as well.

Connection 1 – Tele2 DSL

Davolink DSL modem/routerI’m naming my ISPs in this post because there are some specific issues with some of them. Tele2’s Davolink modem/router for instance needs a little work in order to get it working with the Draytek.

Because Tele2 offers VoIP services as well, you can’t bypass the router and have it function as a modem only. In fact, they’ve disabled most of the router’s user interface, so there’s very little you can change at all. Luckily, you can set up a DMZ. Here’s how to set it up. Because both the Davolink and the Draytek offer wifi, you can simply switch wireless networks to get from on to the other. The manuals for both devices contain info on how to accomplish these steps.

  1. Hook up one of the Davolink’s LAN ports to the Draytek’s WAN1 port.
  2. Log into the Draytek’s web interface and set up static IP internet access for WAN1.
  3. Specifiy a fixed IP address in the Davolink’s IP range (192.168.1.x by default).
  4. Log into the Davolink’s web interface and set that IP as the ‘DMZ host’.
  5. Set up the Draytek’s DHCP server to use a different IP range (such as 192.168.2.x).

That’s it. This will route all traffic to the Draytek, while still keeping the router active to handle VoIP.

Connection 2 – Ziggo cable

Motorola SB5120 cable modemMy Motorola cable modem doesn’t function as a router at all. Simply connect it to the Draytek’s second WAN port, and set up internet access for WAN2 using ‘DHCP Client’ mode. Very easy indeed, although you might need to unplug your modem for a few seconds before it accepts the router. Cable modems usually assign themselves exclusively to the first network adapter they come across. Once you plug it back in, that will be the router’s WAN port.

Optional: Create load balancing rules

Dual WAN routers usually offer lots of settings for balancing your traffic over the two connections, and the Draytek is no different. I love that the default settings are to simply balance automatically based on how fast both lines are. But you can also set up rules to specify what kind of traffic goes where. I’ve created only one. It assigns torrent traffic to one WAN connection, so I still have the other one available for other stuff.


  1. Hear, hear!

    I’ve had great results with Draytek routers: Affordable for consumer, SOHO and small business budgets but with features lacking from consumer products — including QoS, VPN, SIP support, many enterprise routing functions.

    Comment by transcontext — May 8, 2009 @ 2:05 am

  2. If I may suggest:
    maybe a mobile internet connection with bluetooth connection to laptop can also help you out. It is cheaper, easier to set up, and you can use your mobile internet connection everywhere you like, so you have benefit of it at the same time! And it will even still work when you’re power got cut off at home (when your batteries are charged of course).

    Comment by Annunaak — May 8, 2009 @ 1:27 pm

  3. Hi Annunaak. I thought about that too. But most 3G providers here in the Netherlands won’t let you tether a phone to your laptop, let alone a whole home network. And since the Draytek router supports 3G USB modems directly, I can always go 3G in the future.

    You’re right about the power outage though… that still kills everything dead of course.

    Comment by Roy — May 9, 2009 @ 6:38 am

  4. I guess this is how we can combine 2 internet connection. Will you get twice data transfer speed also?

    Comment by Notebook — May 16, 2009 @ 5:36 am

    • Yeah, that’ll work. When I had just set it up I fired up some torrents and they were coming in at 7 mbit. One line is 2 (cheap backup cable), the other 5 (DSL), so they were being combined. Really neat.

      Comment by Roy — May 17, 2009 @ 2:09 pm

  5. Does this combine the link speed for just multi-threaded downloads like torrents? Or can you see double the download speed on regular file downloas as well?

    I have two 10Mb/s cable connections in the house here – i would love to try this!

    Comment by Cody — June 16, 2009 @ 1:54 am

    • @Cody: Yes, it does. I’ve seen torrents come in at exactly the combined speed of the two lines. I chose to not do this (by creating a rule that directs all torrent traffic to one line and free up the second one for work), but the default setting get you 20Mb/s.

      Comment by Roy — June 16, 2009 @ 11:21 am

  6. Wow awesome – time to go buy one of these and play around 🙂 Thanks for this!

    Comment by Cody — June 19, 2009 @ 11:49 pm

  7. Wow I’m jealous. I couldn’t find a similar multi-WAN router in the Philippines that would allow USB modem too. My Huawei HSDPA modem is my secondary connection for now. If the multi-WAN router had print server (2 printers) that’d be perfect!

    Comment by Marie — August 25, 2009 @ 2:32 pm

  8. I would suggest the Syswan Duolinks SW24 Router from my personal experience. This router offers load balancing and redundancy and is rock solid once deployed.

    I have been using a few at customer installations and have had no problems after deployment. The tech support was great and helpful when I had to call in for some advise on advanced configuration.

    You can check the product specs at

    Comment by Wanspider — September 20, 2009 @ 4:24 pm

  9. @Cody – No cody. one connection can only use one DSL connection at a time. This means that if you have a torrent connected to 100 users, some will be using one line and the others will use the second line. If you are loading a web-page, a part of the web-page will be downloaded through one connection and the other part through the other. But if you have ONE download running with only one connection it can only use the max speed of one of your WAN connections.
    Though this can be fixed using download accelerators that download pieces creating several connections like DAP (download accelerator plus)

    Comment by JJ — December 2, 2010 @ 9:19 pm

  10. looks pretty good! Now i’m off and try to set it up myself. wish me luck folks…

    Comment by guido — December 23, 2010 @ 11:36 am

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