How to set up automatic internet failover (multi-WAN)
Failover means your network switches to a backup connection on its own when the main one drops, usually within seconds, and switches back when it returns. Here is how to set it up.
You need two things: a second internet connection on a different technology (5G, cable, fiber or satellite) and a router that supports dual-WAN failover. Plug both connections in, set the main line as primary and the backup as failover, turn on a connection health check, then test it by unplugging the main line.
What you need
- A second connection that doesn't share the same weak point. If your main line is cable, a 5G backup is better than a second cable line. See the best backup internet for options from $20/mo.
- A failover-capable router. Options range from mesh add-ons such as eero Signal (about $99.99, needs an eero network and subscription) and the UniFi 5G Backup (about $99) to dual-WAN business routers from Peplink, Ubiquiti, TP-Link Omada and others.
- Power backup for the modem, router and backup device; see do you need a UPS for your modem?.
Step by step
- Put the primary modem in bridge mode (or use its passthrough mode) so your router, not the provider's gateway, handles the network.
- Connect both lines to the router's WAN ports: main line on WAN 1, backup on WAN 2 (or a USB/cellular port).
- Choose failover, not load balancing, unless you want traffic split across both. Failover keeps the backup idle, which matters if it has a data allowance.
- Turn on the health check. The router pings an outside address (for example 1.1.1.1 or 8.8.8.8) every few seconds and switches when it fails. A link light alone won't catch a provider outage.
- Set switch-back rules so traffic returns to the main line once it has been stable for a minute or two.
- Test it. Unplug the main modem's coax or fiber line during a video call and time how long it takes to recover.
Things that break on failover
- Your public IP changes, so VPN tunnels, remote access and IP allow-lists may drop. A business static IP on the main line won't follow you; see static IPs and SLAs.
- 5G backups often use carrier-grade NAT, which blocks incoming connections and port forwarding.
- Calls in progress drop; VoIP phones re-register within a minute or so.
- Data allowances on cellular backups can run out during a long outage.
Simpler options
If a dual-WAN router is more than you need, some providers build backup in: Xfinity Pro adds a 4G LTE backup extender, Spectrum's Invincible WiFi adds 5G backup and a battery, and AT&T Internet Backup is free with AT&T Fiber and an eligible unlimited plan. For offices, see business internet failover.
- eero Signal and Ubiquiti UniFi 5G Backup product pages, 2026
- Provider backup add-on pages (Xfinity, Spectrum, AT&T), Oct 2026
Prices and terms change often; confirm with the provider before you order. How we research
Questions
What is multi-WAN failover?
A router setup with two internet connections where traffic automatically moves to the backup when the main connection fails, and returns when it recovers.
How fast is automatic failover?
With a health check every few seconds, most routers switch within 5 to 30 seconds. Open connections such as calls or VPNs may need to reconnect.
Can I use my phone as a failover connection?
Some routers accept a phone over USB tethering, but a dedicated 5G backup device or plan is more reliable and doesn't drain your phone.
Do I need a special router for failover?
Yes, one that supports dual-WAN or cellular failover. Most consumer mesh systems need an add-on such as eero Signal; business routers usually have it built in.