Why is the office internet slow, and is it the provider?

Test from a cable first

Start by plugging a laptop directly into the switch or firewall with a network cable, close everything else on it, and run a speed test. Do it a few times at different times of day. If the cabled result is close to what your plan promises, the connection is fine and the slowness is somewhere inside your network, most likely the Wi-Fi. Wi-Fi speed tests vary with distance and interference, so they are a poor guide to the connection itself.

If the cabled result is well below your plan, keep going. Try the test with the business firewall bypassed if that is practical, by connecting directly to the provider's equipment. If speed jumps, the firewall is the bottleneck, often because it is too small for the connection once security features are switched on.

Look at latency, not just speed

Speed tests show download and upload, but latency, measured in milliseconds, often explains why calls stutter and web pages hesitate. A good fibre connection usually shows low, stable latency. If latency jumps dramatically while a speed test is running, the connection is saturated and other traffic is queuing behind it, which is called bufferbloat.

Upload speed deserves attention too. Video calls, cloud backups and file sync all send data out of the office. Many fibre plans have far lower upload than download, and one large backup or a staff member uploading video can fill the upload completely, making every call in the office choppy even though download looks fine.

Find the bandwidth hog

When everything is slow at certain times, something is usually using most of the connection. Common culprits are cloud backups that run during the day, Windows and Mac updates downloading on many machines at once, staff syncing large folders to OneDrive or Google Drive, security cameras uploading footage to the cloud, and the occasional personal streaming session.

A business firewall can show you which device or application is using the bandwidth right now and over the past day. Without one, you can check the backup schedule, move large syncs to after hours and use the firewall or router's quality of service settings to give calls and business applications priority.

When it really is the provider

The provider is the likely cause if a cabled test with no other traffic is consistently slow, if speeds drop sharply at the same times each evening or morning, or if the connection drops completely and the provider's equipment shows warning lights. Note the times, keep screenshots of test results and check the provider's status page for known outages in your area.

When you call, explain that you have tested from a cable with the business equipment bypassed. That skips the first round of basic troubleshooting and gets the fault to the people who can fix it faster. Ask for a fault reference number and keep it with your notes. If faults repeat, ask whether the provider can check the line or the fibre equipment remotely and share what they find.

Check the old technology in the chain

Some offices still have connections that were never upgraded, or a plan that suited five staff and now serves twenty. With copper services being withdrawn across New Zealand, check whether your connection is still on old technology and what fibre or fixed wireless options are available at the address. Moving from an old copper or entry-level plan to a current fibre plan is often the single biggest improvement an office can make.

Inside the office, old network gear can cap speed too. A firewall or switch with only 100 megabit ports, a damaged patch lead that negotiates at a lower speed, or an ancient Wi-Fi access point can each make a fast connection feel slow. Checking the link speed reported on each device is a quick way to spot these.

Fixing it for good

Once you know where the problem is, the fix is usually straightforward: improve Wi-Fi coverage, upgrade an undersized firewall, schedule heavy traffic for after hours, set quality of service for calls, or move to a faster plan with better upload. Sometimes a second internet connection makes sense, both for speed and for resilience.

If you want a clear answer without the trial and error, a technician can run these tests in the office, read the firewall and switch statistics, and tell you exactly where the bottleneck sits and what it will take to remove it. That report also tells you whether spending money on a faster plan will help at all, or whether the fix is inside the building and costs less than you feared.