Unifi Speed Stuck Around 100 Mbps? Check the Ethernet Link
If your Unifi plan is faster than 100 Mbps but a wired test repeatedly stops around 90–100 Mbps, check the Ethernet link between the computer and router first. A 100 Mbps local link is a useful clue, not proof that Unifi has capped the line. The cause can be an adapter, port, cable or an intermediate device.
This guide focuses on a repeated wired ceiling. If internet access is completely unavailable, start with Unifi connection troubleshooting. If the problem is only weak WiFi in a distant room, use our broader Unifi speed improvement guide.
Link speed and internet speed are different
Link speed is the connection negotiated between two local Ethernet ports. An internet speed test measures transfers across the whole route to its test destination. A 1 Gbps local link does not guarantee 1 Gbps internet, while a 100 Mbps segment can constrain an otherwise faster route. Protocol overhead means application throughput is lower than the raw link rate.
First confirm that your subscribed package is above 100 Mbps. A result close to a 100 Mbps plan’s rate is a different situation from a 500 Mbps subscription consistently stopping at the same level. Also check the units: 100 Mbps is 12.5 MB/s before overhead. A downloader displaying MB/s cannot be compared directly with a speed test displaying Mbps.
1. Read the Ethernet connection’s negotiated speed
On Windows, search for Control Panel, open Network and Sharing Center, then select the active Ethernet connection to view its Status and Speed. Menu labels can vary by Windows version. Make sure you are inspecting Ethernet rather than the WiFi connection.
For Intel Killer adapters, Intel’s Ethernet link-speed troubleshooting guidance explains how a 100 Mbps negotiated link can limit a faster connection, and recommends checking cable and port combinations. Use your adapter manufacturer’s instructions for other hardware.
| What you see | What it tells you |
|---|---|
| 100 Mbps local link | Investigate the local wired path before judging a faster broadband plan. |
| 1.0 Gbps local link | The computer’s current local link is gigabit; another segment or a different bottleneck can still limit throughput. |
| Link rate changes after swapping a cable | The changed cable or its connection becomes a strong lead to investigate. |
| WiFi connection selected | This is not an Ethernet link-speed reading; repeat with the wired adapter. |
2. Make one short, known-good wired path
Connect a capable computer to a known gigabit-capable LAN port on the router with a known-good cable. Temporarily remove optional switches, wall extensions, powerline adapters or docking stations from this comparison. Leave the broadband router and fibre equipment configured as supplied; you do not need to connect a laptop directly to a bare fibre terminal.
Check the negotiated link again before running another test. If it improves, reintroduce one bypassed component at a time. That tells you more than replacing several things together. Stop if a connector is damaged; do not bend pins or open provider equipment.
3. Check the complete chain
A gigabit router is not enough if the USB adapter, switch or another port in the path only supports 10/100 Ethernet. Read the specifications of the exact model and port, rather than assuming every socket has the same capability. A cable that worked previously can also develop a fault.
For compatible Intel adapters, Auto Negotiation is the recommended setting in the cited guidance. Do not force a speed or duplex value as a universal fix. Record the original settings and use the manufacturer’s instructions if a change is needed.
4. Repeat the internet test under controlled conditions
Once the local link is correct, pause other transfers, disconnect a VPN for the comparison and run the Unifi speed test on the wired computer. Record the local link rate beside the result. Each test consumes data, so a small number of deliberate comparisons is more useful than repeatedly pressing START without changing the conditions.
If Ethernet is now substantially faster, the earlier ceiling was consistent with a local bottleneck. If every capable device remains slow with a correct local link, document the result for Unifi rather than declaring the router or provider guilty from one reading. Our speed-test results guide explains how to interpret those comparisons.
Quick record to keep
- Subscribed package and test time.
- Computer, adapter and router LAN port used.
- Negotiated Ethernet rate before and after the change.
- Whether a switch, dock or wall connection was bypassed.
- Download/upload results and whether background traffic was paused.
What if my plan is above 1 Gbps?
A 1 Gbps Ethernet segment cannot carry a greater raw rate just because the broadband package is faster. Check the multi-gigabit capabilities of the router port, adapter and intervening equipment. A bounded browser test can also underestimate a very fast connection, so follow any measurement method requested by your provider.
Does this also apply to other providers?
The Ethernet comparison applies regardless of the brand on the bill. If the active connection is Maxis or CelcomDigi, use the corresponding Maxis connection test or Digi/CelcomDigi connection test. The tool measures whichever network the device is actually using; it does not select a provider for you.