Case Studies / Latest Case The Router Port Lit Up and the Desktop Still Had No Internet: a Missing Network Driver After a Windows Reset (Occom 25M, Eastgardens)
On-site · EastgardensOccomOpticomm fibre + PPPoE25 Mbps planASUS routerMissing network driver
The link light on the router came on the moment the cable went in, which is exactly why this one was confusing. A lit port means the cable and the two sockets are electrically fine — it says nothing about whether the computer can actually use the connection. Everything on the network side was healthy here. The fault was inside the desktop, and it had been created the day before.
A lit port is not the same as a working connection
This is the single most useful thing to take from this job. When you plug a cable in and the router's port light comes on, three things have been proven: the cable is intact, the router's socket works, and the computer's socket is powered. That is all.
Everything above that — whether Windows can see the adapter, whether it has a driver, whether it can obtain an address — is invisible to that little light. So a lit port with no internet is not a contradiction. It is a fairly precise clue that the physical layer is fine and the problem lives further up, usually inside the computer.
Which link was actually failing
→
→
ASUS router & LAN port
link light on
→
Desktop network adapter
no driver
Faulty here
→
Four of these five links were doing their job, and the one that was not sits inside the computer where most network troubleshooting never looks. This is why we carry a test device: plugging our own laptop into the same cable and the same port took the entire network side off the table in under a minute, and left only one place for the fault to be.
How a system reset takes the network with it
The customer had reset their Windows installation the day before. That is the whole story of this fault.
A fresh Windows install brings generic drivers for common hardware, but a desktop's onboard network adapter is one of the components most likely to come out of it without a working driver. And it is the worst one to lose, because the usual way to fix a missing driver is to download it — which you cannot do from a machine that has no network at all. The customer had also not been able to join the WiFi, which fits: the adapter, not the connection, was the thing that was broken.
If you are about to reset a desktop, download the network adapter driver from the manufacturer's site first and keep it on a USB stick. It turns this from a call-out into five minutes.
How we isolated it on site
1
Checked the main router and its ports with our own test device
Router, cable and port all fine
2
Same cable, same port, customer's desktop — nothing
Fault is inside the PC
3
Looked at the network adapter in Windows
Driver not working
4
Customer mentioned the system had been reset the day before
Explains the missing driver
5
Downloaded and installed the network adapter driver
Adapter now recognised
6
Connection kept coming up then dropping
IP allocation looked abnormal
7
Reset the router and reconnected
Desktop stable and online
8
Replaced the wireless extender with a wired second router
Wired to the PC, new SSID for the room
The second problem, hiding behind the first
Installing the driver got the adapter recognised, but the desktop still would not settle: it connected to the router and dropped again almost immediately, over and over.
Two faults in a row is more common than people expect, and it is easy to assume the first fix did not work. It had — the adapter was fine now. What we were looking at was the router handing out addresses abnormally, so we reset it and reconnected, and the desktop stayed up. The lesson is to check whether the symptom has actually changed after each step. "Still no internet" and "connects then drops" are different symptoms, and treating the second one as a failure of the first fix sends you backwards.
Fixing the coverage while we were there
The customer also had a WiFi extender in use. Extenders repeat the signal wirelessly, so whatever they receive is what they pass on — in a room the main router already struggles to reach, that means a weak signal repeated weakly.
There was a spare TP-Link router in the flat, so we configured it as a second router in the bedroom, fed by a cable rather than over the air. The desktop now plugs straight into it and tests fine, and the room gets its own wireless coverage as well. No new hardware was needed — just using what was already there in a better way.
Wireless extender or a wired second router
| Wireless extender (what they had) | Wired second router (what we set up) |
|---|
| How it reaches the main router | Over the air, repeating the signal | Over a cable |
| Signal quality in the room | Poor — only as good as what it receives | Independent of the main router's coverage |
| Wired port for the desktop | Not what it is for | Straight into the PC |
| Extra hardware needed | The extender | A spare router they already owned |
| What it needs from the flat | Nothing | A cable run to the room |
What to take from this one
- A lit port proves the cable and the sockets, nothing more. Do not let it talk you out of suspecting the computer.
- Test with a device you trust. Plugging a known-good laptop into the same cable and port clears the entire network side in under a minute.
- Say what changed recently. "I reset the system yesterday" was the single most useful sentence of this visit.
- Download the network driver before you reset a PC, and keep it on a USB stick. A machine with no network cannot fetch its own network driver.
- Watch whether the symptom changes after each fix. Connecting and dropping is not the same failure as never connecting.
- A wired second router beats a wireless extender whenever you can get a cable to the room, and often the spare router is already in the cupboard.
Result
The desktop came back online over a wired connection after the network adapter driver was installed and the router was reset to clear the abnormal address allocation, and the bedroom now has a wired second router in place of the wireless extender — the PC plugged straight into it, with its own wireless coverage on top. About an hour and a half on site, with no new hardware bought.