Solutions

If I needed 5G for broadband backup and failover

Keeping a business online when the fixed line drops: how I would add 5G failover so card machines, phones and cloud apps carry on without anyone noticing.

Nick Appleby October 13, 2026 2 min read

The short answer

I would put a 5G router with automatic WAN failover between the fixed line and the network, give it a SIM on a different network to the fixed line provider where possible, and test the switchover properly before calling it done.

The problem

When the broadband goes down, card payments, VoIP phones and cloud systems all stop together. The cost of a few hours offline usually dwarfs the cost of a backup connection.

The common mistake is a backup that has never been tested, or one that needs someone on site to swap cables when the line fails.

Here is what I would do

  1. Decide what has to stay up Usually payments, phones and core cloud apps. That tells you how much speed the backup really needs.
  2. Choose how the 5G joins the network Either replace the main router with one that takes both the fixed line and a SIM, or add a 5G router as a second WAN on your existing firewall.
  3. Use different paths Avoid backing up a line with a service that shares the same street cabinet or provider fault. A mobile SIM is a different path by nature.
  4. Set failover and failback rules Use health checks that ping real internet hosts, not just the modem, and decide whether the site moves back automatically once the line returns.
  5. Get the antenna right If the router sits in a comms room, an external or window-mounted antenna makes the backup actually usable.
  6. Test it Pull the fixed line cable during a quiet hour and check that payments, phones and remote access all keep working.

The kit I would use

  • RouterBusiness 5G router with multi-WAN failover

    Ethernet WAN for the fixed line, SIM for 5G, and health checks that switch automatically.

  • SIMBusiness data SIM, ideally dual SIM

    A second network in the second SIM slot covers a mobile network outage too.

  • AntennaPanel or MIMO antenna

    Only if the router lives somewhere with poor indoor signal.

V2865LAX-5G-KDrayTek Vigor V2865LAX-5G-K 5G Router with Wi-Fi 6 and Dual SIM Slots£647.00In stockDraytek Vigor 2927Lax-5G-K 5G Router with WiFi6Draytel Vigor 2927Lax-5G-K 5G Router with WiFi6£719.00In stockNebula FWA510 5G RouterNEBULA FWA510 from Zyxel - 5G Router with WiFi6 and external 5G antenna connections (4x4 MiMo)£345.00In stockRUTX50Teltonika RUTX50 5G Router£379.00In stock

See the full range →

What I would avoid

  • A backup nobody has tested. Failover that has never been tried usually fails the first time it matters.
  • Pay-as-you-go SIMs that run out of credit while sitting unused for months.

Not quite your job?

Every site is a little different. Tell us where it is, what needs connecting and what has already been tried, and we will tell you what we would do. Get in touch.

Questions people ask

Will my phones and card machines switch over automatically?

With a router that has automatic WAN failover, yes. Some VoIP systems re-register within seconds; others take longer, which is why testing matters.

Can 5G be my main line and fixed broadband the backup?

Yes. Where 5G is faster than the available fixed line, many businesses run it the other way round.

Does the backup SIM cost much when it is not being used?

Low-data backup plans exist for exactly this. Pick a plan sized for how long an outage could realistically last.