Most building sites will never see a fixed broadband line. The job is too short, the line is too slow to arrive, or the site is somewhere a line was never going to reach. But the site still needs to work: drawings on a screen in the cabin, timesheets and photos going back to the office, email, Teams calls with the architect, and the site manager’s laptop doing everything their desk at head office does.
So what actually works? The short answer is satellite internet as the main connection, 4G as the backup, and a setup that stays secure whichever one is in use. The longer answer is in the detail, because the detail is where site internet usually goes wrong.
Start with what the site can actually get
Before buying anything, find out what signal the site really has. Mobile coverage maps are a starting point, not an answer. Ofcom’s Map Your Mobile checker shows predicted 4G and 5G coverage by postcode for each of the four networks, indoors and outdoors. It is worth checking, but predicted coverage and what you get standing in a field are not the same thing.
On one of our clients’ sites, the coverage maps looked fine. On the ground, one network was unusable and only one 4G network gave a workable connection. You only learn that by testing on site, with phones or a test router on each network, at different times of day.
The cabin itself can block the signal
Site cabins are steel boxes. A 4G router sitting on a desk inside one can lose most of the signal that is available a few metres away outside. That catches a lot of firms out: the signal test was done outside, the router went inside, and the connection was poor from day one.
The fix is simple: mount the antenna outside the cabin, on the roof or a short pole, and run the cable in. An outside antenna on the one network that works is often the difference between a 4G connection you can rely on as a backup and one you cannot.
Satellite as the main connection
Low-orbit satellite internet has changed site connectivity. A dish on the cabin roof gives broadband-class speeds almost anywhere with a clear view of the sky, and it can be up and running in a day rather than waiting weeks for a line. For most sites, it is now the sensible main connection.
It has limits. The dish needs a clear view of the sky, so cranes, scaffolding and tall trees can interrupt it as the site changes. It needs power, which matters when the generator goes off (we cover that in keeping site internet on after hours). And like any single connection, it will occasionally drop.
4G as the backup, not the plan
The right design is satellite first, 4G second, with a router that switches between them automatically. When the dish loses its view of the sky or has a fault, the site keeps working on 4G and nobody has to do anything. When the dish comes back, the router switches back.
4G on its own is rarely enough as the only connection for a busy cabin. Drawings, video calls and photo uploads add up, and a single mobile connection shared by a whole site team struggles. As a backup for a few hours, it is fine.
Keep the security working when the connection changes
This is the part most site setups miss. Many firms protect their office systems by only trusting connections from known internet addresses. A site on satellite and 4G does not have a fixed address. It changes when the router switches connection, and it can change on its own.
If the security depends on a fixed address, one of two things happens. Either the site gets locked out every time the address changes, or someone weakens the rules so the site can get in, and the protection quietly disappears. Neither is acceptable.
The better approach is security that follows the user and the device rather than the address: multi-factor sign-in, company-managed laptops, and rules that update themselves when the site’s address changes. The site manager signs in the same way on site as in the office, and nobody has to phone IT when the connection switches.
Give subcontractors their own Wi-Fi
Subcontractors will ask for the Wi-Fi password. Give them a separate guest network, not the one your laptops and printer use. A guest network keeps their devices away from yours, and you can change its password at the end of each job without disrupting your own team.
A simple checklist for the next site
- Test every mobile network on site, outside and inside the cabin, before choosing
- Use satellite as the main connection where the site has a clear view of the sky
- Add 4G on the best network as an automatic backup, with an outside antenna
- Make sure security is based on the user and the device, not a fixed internet address
- Put subcontractors on a separate guest network
- Plan for power when the generator is off
If you are setting up a new site and want a second opinion, we do this for construction firms across Northern Ireland. See IT support for construction companies.
Related: Can a site cabin keep its internet on when the generator goes off?
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