Dual WAN failover and backup internet for small businesses

Your network gets a second internet connection, plugged into a gateway that can use two. That is what dual WAN means: a main line and a backup on one gateway.

The gateway keeps checking the main line. When it stops answering, the gateway moves your traffic to the backup. When the main line comes back, it moves the traffic back. Nobody has to be there to swap a cable.

The switch usually takes somewhere from a few seconds to a minute or so, depending on the equipment and how the checks are set. What it catches depends on those checks, too. A line that's down is easy to spot. A line that's up but crawling may not trigger a switch.

If the gateway you have can't handle two connections, I'll tell you, and quote one that can.

More about the UniFi equipment I usually use

Usually one of these, each with its trade-offs:

• A second wired provider. Better if it's a different technology from the main line, such as cable plus fiber or DSL where they're available. Two lines of the same type can share the same run down the street, so one cut can take out both.
• Cellular (LTE or 5G). A cellular router or modem with its own data plan. It needs a decent signal where it sits. Many plans have data caps, or slow down when the cell network is busy.
• Satellite. A service such as Starlink. The dish needs a clear view of the sky. Trees and the roofline can get in the way.

What's available depends on the address. I check what you can actually get at yours and help you choose, and you sign up in your name. The backup line is your own account with the provider, billed to you.

Browsing, email, cloud apps, and most VoIP phones usually carry on once the gateway has switched. Whatever is open at that moment may drop and reconnect. A video call can freeze for a moment and rejoin.

Some things depend on the main line's own address. They may not work on the backup unless they're set up for it:

• A static IP address from your provider.
• Remote access into the office from outside.
• A VPN tied to the main line's address.
• A camera or a server that people reach from outside the building.

If any of those matter, tell me, and I'll work out what can be set up to use the backup. On a capped cellular plan, where the gateway supports it, I can also limit data-heavy traffic, such as cloud backups and large updates, to save the plan for the work that needs it.

It earns its keep where no internet means no work:

• Card terminals or a point-of-sale system that runs in the cloud.
• VoIP phones.
• Practice-management or job software that lives in the cloud.
• People working from home who can't miss a call.

If an outage now and then is an annoyance rather than a cost, a phone hotspot may be all you need, and I'll say so.

Before hand-off, I test it the plain way: unplug the main line and watch the gateway move to the backup, then plug it back in and watch it move back.

Where the gateway supports it, I also set up a notification for when it switches over.

After that, check every so often that the backup's plan is still active and paid. Cellular plans in particular can lapse, leaving the backup unavailable when it's needed.

A power outage can take the network equipment offline, so a backup line alone may not help.

A UPS, a battery backup that plugs into an outlet, can keep the modem, the gateway, and the switch running for a while, if it is sized for them. The connection also depends on the provider's equipment staying up. I can include a plug-in UPS for the network equipment. A new outlet or circuit for it is electrical work, so it goes to a licensed electrician.

Failover that has been tested, and what you need to run it without me:

• The admin logins for every piece of equipment.
• A labeled port map, so anyone can tell which cable goes where.
• A one-page written summary of the setup, listing both internet providers and the account details for each.

No lock-in: anyone competent can pick it up later.

You can buy the hardware yourself from a parts list I provide, or I supply it at cost plus a small markup, with a 50% deposit on the equipment and the rest due on completion.