5G Router for Office Broadband: What Works and What to Avoid

Offices end up on 5G for all sorts of reasons. The building is new and the fixed line is months away. The street has never had decent broadband. The company has moved into serviced space and does not want to be tied to the landlord’s network. Or the fixed line keeps failing and someone has finally had enough. Whatever the reason, the questions are much the same.

Can 5G really replace office broadband?

Often, yes. Where there is good n78 coverage, a business 5G router with properly installed antennas can deliver download speeds in the hundreds of megabits and upload speeds that comfortably outpace older copper broadband. For a small or medium office that mostly uses cloud software, email, video calls and file sharing, that is plenty.

Where it gets harder:

• Coverage is weak or 4G only. Performance will be more like a decent home connection, and it will vary through the day.
• Heavy upload. Offices that upload large files constantly, run lots of video calls at once or host services inbound will feel the limits sooner.
• Consistency. Mobile networks are shared. Performance at 5pm near a busy station may be very different from 9am.
• Inbound services. Hosting a server, VPN endpoint or remote desktop on standard mobile SIMs does not work without a public IP or a workaround.

How many people can a 5G router support?

It depends far more on what they do than how many there are. A rough way to think about it:

Not everyone is active at once. A 20 person office with a reliable 100 Mbps down and 30 Mbps up will usually feel fine. The pinch point is almost always upload during video calls, so pay more attention to upload speed and latency than to download.

Office setups that work

5G as the main connection

A business 5G router with an external antenna mounted outside or high on a window. Dual SIM or a multi-network SIM so a network outage does not take the office offline. A generous data allowance, because offices use more than people expect. A separate Wi-Fi system if the office is more than a single room.

5G as backup to fixed broadband

The router connects to the fixed line as primary and uses 5G only when the line fails. This is the most common office setup and the easiest to justify. See 5G backup and failover.

5G alongside fixed broadband, both in use

Some routers can load balance across a fixed line and 5G, or send certain traffic, such as guest Wi-Fi or backups, over one and business traffic over the other. This gets more value from the 5G connection than leaving it idle as a backup.

Temporary office

A site office, project office or new premises before the line goes in. The router needs to be quick to install and easy to move. Bring a portable external antenna or a short mast, and test a couple of locations before settling.

Placement makes the difference

The most common office mistake is putting the 5G router in the comms cupboard next to the old broadband router, closing the door and wondering why it is slow. n78 5G does not pass through walls well, and many office buildings have metallised glass that blocks it even more effectively.

The fix is usually simple. Mount an external antenna on an outside wall or the roof, or on the inside of a window facing the nearest mast, and run a short cable to the router. Connect all four antenna ports. The difference can be dramatic: we regularly see routers go from tens of megabits to hundreds just by moving the antenna.

See the 5G antenna guide and adding an external antenna for detail on antenna choice and cable loss.

Phones, VoIP and Teams

Voice and video calls work well over 5G in reasonable coverage. They are sensitive to latency, jitter and packet loss rather than raw speed, so it pays to:

• give voice traffic priority on the router if it supports QoS
• keep the upload from being saturated by backups or file sync during the day
• test call quality at busy times, not just speed
• check that your VoIP provider is happy with mobile IP addresses and carrier-grade NAT

Most hosted VoIP services cope fine with NAT. Some older on-premises phone systems with SIP trunks can be fussier and may need a fixed IP SIM or specific configuration.

Data allowances

A typical office uses more data than anyone guesses. Cloud backup, software updates, video calls and file sync add up quickly. As a rough guide, a small office of ten people doing normal office work might use several hundred gigabytes a month. Heavy video or design work can push that much higher.

Look at the existing broadband usage if you can. Most routers report it. Then choose a 5G data plan with plenty of headroom, because hitting a cap mid-month is a much bigger problem than paying for a bit more than you need.

Security for a 5G office

A 5G connection is no less secure than a fixed one, but the router needs to be set up properly. Use the firewall, keep firmware updated, separate guest Wi-Fi from staff, and use VPNs rather than port forwarding for remote access. If staff connect into the office from home, a VPN on the router or a cloud remote access service is the right approach.

Fixed IP for offices

Some offices need a fixed public IP address: for an IP-whitelisted supplier portal, a VPN that partners connect into, a phone system or a hosted service. Standard mobile SIMs will not provide this. You need a SIM with a public static IP, or a router service that provides one through a VPN tunnel. See public and static IP on 5G.

Checklist for an office 5G setup

1. Test signal at the building, ideally at the point where the antenna will go.
2. Choose a business router with four external antenna connectors.
3. Plan the antenna position and cable route before ordering.
4. Choose a SIM with enough data and the right IP type.
5. Decide on failover: second SIM, fixed line or both.
6. Set up the firewall, VLANs and QoS for voice.
7. Test speed and call quality at busy times.
8. Pull the fixed line, if there is one, and check failover works.

Serviced offices and shared buildings

Businesses in serviced offices and multi-tenant buildings often use 5G to get independence from the landlord’s network. That is a perfectly good reason, but shared buildings have their own challenges. You may not be allowed to fit an external antenna on the outside of the building, and cable routes may be restricted. Coated glass in modern buildings can make indoor 5G particularly poor.

Options include a window-mounted antenna on the inside of the glass facing the mast, a router positioned at the window with its own antennas, or negotiating a small antenna on the roof with a short cable to a router in a riser cupboard. Ask the building manager early, because approvals can take time.

Wi-Fi in a 5G office

Many 5G business routers have built-in Wi-Fi, and in a single room it may be all you need. In larger offices, the router is usually in a poor spot for Wi-Fi coverage, because it has been placed for the best mobile signal rather than the best Wi-Fi position. Use the router as the gateway and firewall, and run proper access points from a switch. Keep guest Wi-Fi on its own VLAN with its own bandwidth limits, so visitors streaming video do not affect business traffic on a shared 5G connection.

When 5G is not the right answer for an office

If full fibre is available at a sensible price, it will usually be cheaper per gigabyte, more consistent and better for heavy upload. 5G then makes a superb backup. If the office is in a 5G blackspot, the router will run on 4G, which may still be better than a poor copper line but will not transform anything. Be honest about the coverage and the workload, and 5G will rarely disappoint.

If you are planning 5G for an office and want a sense check, email sales@5grouter.co.uk.