What Was Happening
The Wi-Fi icon showed connected. Network name displayed correctly. Signal strength normal. But every browser said “this site can’t be reached” and every application that needed the internet behaved as if the laptop was offline.
The customer had already tried the standard self-help steps: restart the router, restart the laptop, forget and rejoin the network. None of them changed anything. They had checked their phone on the same Wi-Fi — phone worked fine. The problem was specific to this laptop.
Our Diagnosis
The classic ‘connected, no internet’ fault has several possible causes, each in a different layer of the network stack:
- Layer 1 — physical. Adapter hardware. Reaching the router at all means this layer is fine.
- Layer 2 — data link. Authentication with the router (the Wi-Fi password). “Connected” status means this layer is fine.
- Layer 3 — network. IP address assignment, default gateway, routing. A missing or wrong default gateway here causes “connected but no traffic flows”.
- DNS. Name resolution. A working network with broken DNS gives “connected but pages won’t load” — pages by IP address work; pages by name don’t.
- Application/security software. A firewall, VPN, or antivirus blocking traffic.
Diagnostic in that order:
- Check the IP configuration.
ipconfig /allshowed a valid IP address from the router and a correct default gateway. Layer 3 looked fine. - Ping the gateway — succeeded. Confirmed layer 3 connectivity to the router.
- Ping a public IP address (8.8.8.8). Succeeded. Confirmed routing beyond the router to the public internet was fine.
- Ping a public name (google.com). Failed with “could not find host”. DNS layer broken.
- Check DNS configuration. Found DNS servers configured but with an additional entry pointing to a localhost address from a previously-installed VPN product.
So far, so identifiable. But fixing just the DNS would have left the underlying network stack damage in place. So we kept looking:
- Examined the Winsock catalog. Found entries from a third-party VPN that had been uninstalled but had left its driver and configuration behind.
- Examined the routing table. Found stale routes from the same VPN that were redirecting traffic to nowhere.
Root cause: a third-party VPN product that had been uninstalled cleanly from the Programs list but left behind drivers, registry entries, routing rules and Winsock catalog entries that were collectively breaking the network stack.
How We Fixed It
The fix walks through the network stack and resets each layer cleanly:
- Removed the residual VPN drivers from Device Manager and from the Windows driver store.
- Reset the Winsock catalog with
netsh winsock reset— restores Winsock to its default state, removing third-party layered service providers. - Reset the TCP/IP stack with
netsh int ip reset— restores TCP/IP to defaults. - Cleared the DNS cache with
ipconfig /flushdns. - Removed stale routing entries with
route -f(carefully — this requires recreation of any legitimate static routes the user had, but in this case there were none). - Removed and re-added the Wi-Fi network profile so the laptop forgot any cached configuration for this network.
- Refreshed the network adapter drivers with the latest from Lenovo’s driver bundle for this model.
- Restarted to let everything take effect cleanly.
After restart: laptop connected to Wi-Fi, all layers verified clean, pages loading normally with sensible latency.
The Result
Full connectivity restored. Browsers loading pages normally, applications connecting normally, no DNS errors. The laptop has been on the same Wi-Fi network without issue since.
Why This Happens
Third-party VPN software is the single most common cause of leftover network stack damage. VPN products install themselves deeply into Windows — they need to, in order to intercept all network traffic — and many of them uninstall poorly. The user removes the VPN, thinks the system is back to defaults, and then has weird intermittent network issues for months afterwards without obvious cause.
Other common culprits:
- Third-party firewalls that have been uninstalled. Same residue problem.
- Antivirus products that bundle network protection. McAfee, Norton, Kaspersky and others have all had versions that leave network filter drivers behind after uninstall.
- Old WiFi-management utilities from the laptop manufacturer that conflict with Windows’ built-in network management.
- Schools and workplaces. Laptops that were previously managed by an IT department often have configuration that survives the user’s departure — VPN profiles, certificate stores, proxy settings.
- Failed DNS providers. Less common, but a configured DNS server that has become unreachable will give exactly this symptom.
How to diagnose this yourself
If you’ve got ‘connected, no internet’:
- Check other devices on the same network. Phone, another laptop. If they work, the problem is your laptop, not the network.
- Open Command Prompt and try
ping 8.8.8.8. If that succeeds butping google.comfails, you have a DNS problem. - Try
netsh winsock resetfollowed by a restart. Solves more cases than people realise. Safe — it just resets Windows networking to defaults. - Check Device Manager for any drivers from VPN or security software you’ve uninstalled. Remove them.
- If you’re still stuck, the next steps are routing table, network profile reset, and a driver refresh — at which point a workshop call is usually the right answer.
Local Help in Barnes SW13
Wi-Fi connectivity faults usually trace back to one of a small number of causes — and a workshop diagnostic separates them quickly.
We diagnose router-side issues, laptop-side network stack damage, leftover-software conflicts and full home or office Wi-Fi setups from our Putney workshop.
Drop in to SW15, call 020 7610 0500, or contact us to discuss.