A very specific kind of Wi-Fi call comes in from households out towards Cockenzie, Port Seton and the coast: one desktop or laptop insists it has no internet, the little globe in the system tray shows a yellow triangle and the words “Connected, no internet” or “No internet, secured”, and yet the phones in the kitchen and the Sky Glass in the front room are perfectly happy on the same Wi-Fi. Restarting the router does nothing. Restarting the PC does nothing. Whatever it is, it is only on that one machine. If that is what you’re staring at right now, this is what we do when a home visit in Cockenzie is booked for exactly this pattern.
The reason this is worth its own guide rather than a “have you turned it off and on again” page is that the message is telling a small lie. Windows does not know whether you have internet or not. It runs a probe every so often, decides based on the answer, and then paints a coloured icon and refuses to let some apps run until the answer changes. When one PC gets the wrong probe result, everything downstream of that flag falls over — the Store, OneDrive, Outlook, Windows Update, half the modern apps in the Start menu — even though your browser can still load pages if you type a URL in.
What ‘Connected, No Internet’ Actually Means
Windows has a component called the Network Connectivity Status Indicator, NCSI for short. When you join a Wi-Fi network, NCSI reaches out to a small Microsoft server — historically www.msftncsi.com, and on modern Windows www.msftconnecttest.com — and does two checks. It asks for a plain text file that should contain the exact string Microsoft Connect Test, and it asks for a DNS lookup that should return a specific IP address. If both come back correct, the network is flagged as having internet. If either fails, or comes back with the wrong content, Windows paints the triangle.
That is worth reading twice. The yellow triangle does not mean packets are not flowing. It means one small automated test to one specific Microsoft address did not return the specific answer expected. The rest of the internet could be entirely reachable, and often is.
Why It Is One PC and Not All of Them
Phones and TVs run their own connectivity checks — iPhones probe captive.apple.com, Android probes a Google URL, Sky and modern smart TVs ping their own back-end — and they don’t care about the Microsoft probe at all. So if something on the network is interfering only with Microsoft’s probe URL, every non-Windows device will look fine while the Windows machine will look broken. That is the single most common source of the “one PC only” pattern.
Even between two Windows PCs on the same Wi-Fi it can differ, because the failure is usually a per-machine one: a static DNS server saved on that particular network adapter, a leftover proxy setting from a school laptop’s time on a different network, a VPN client that’s technically off but still holding the routing table, a security suite whose web-filter has an out-of-date cache, or a Winsock catalog corrupted by an interrupted Windows Update. Those are all local to the machine. Nothing on the router touches them.
The Two-Minute Sanity Check
Before touching any settings, we always run the same three-question test on the affected PC. It takes a couple of minutes and it tells you which layer to look at next.
First, open a browser and try to reach a plain IP address — 1.1.1.1 is the easiest. If that loads a page, the internet itself works and only the name lookup or the probe is broken. Second, open PowerShell and type nslookup google.com. A clean answer with an IP address in it means DNS is fine and the problem is narrower than DNS. A timeout or a “can’t find server” error means the machine can’t look names up, which is a DNS problem to fix on the machine or the router. Third, type ping msftconnecttest.com. If everything else works but only that host fails, the probe itself is being blocked — which is why the triangle is stuck.
Those three answers, in that order, sort the callout into “router problem”, “DNS problem” or “probe blocked” before we’ve changed a single setting. That’s the same discipline we walk through in the wider home Wi-Fi troubleshooting guide: measure, then fix.
The Usual Suspects, in Order
A stale static DNS from an old fix. The single most common cause on machines that used to work. Someone typed Google’s 8.8.8.8 or Cloudflare’s 1.1.1.1 into the adapter properties months or years ago to work around a different problem, the ISP has since changed its router, and now the machine is trying to resolve names against a server the new router quietly blocks. Clearing that back to “Obtain DNS automatically” fixes it in seconds.
A leftover proxy setting. Ex-work laptops, ex-school laptops and Windows installs that once ran a browser plugin often have a proxy configured that points nowhere useful. Windows will try to send every request through it, get no answer, and flag the network. Internet Options → Connections → LAN Settings, and turn everything off unless you know you need it.
A VPN client that thinks it’s off. NordVPN, ExpressVPN, corporate Cisco AnyConnect, the built-in Windows VPN client — all of them can leave a virtual adapter in place after a disconnect that still routes traffic into a tunnel that no longer exists. The give-away is an unknown adapter in ipconfig /all with a tiny subnet like 10.8.0.0. Uninstall or reset the VPN client fully and it clears.
A Winsock catalog broken by an interrupted update. Rarer, but a certainty on machines that lost power mid-update or had an antivirus scrub a Windows component it thought was malware. netsh winsock reset, netsh int ip reset, and ipconfig /flushdns in an elevated PowerShell, then reboot, brings the stack back cleanly. The fix is boring because that’s the point — the stack is stateful and sometimes needs a fresh start.
A router-level DNS filter blocking the probe. The trickier one, and increasingly common with ISP-supplied routers pushing DNS-over-HTTPS by default. If everything else on the machine is clean and only msftconnecttest.com is unreachable, the router itself is intercepting the check. That’s a router config fix, not a PC one, and it’s where these jobs stop being software troubleshooting and become networking and Wi-Fi work proper.
A Recent Callout at the Cockenzie Harbour
A retired customer with a view over the old power-station site rang the workshop after a fibre upgrade. Openreach had come, installed the new router, everything on the phones and the tablet worked immediately, but the Windows 11 desktop in the spare room showed “No internet, secured” on the Wi-Fi and refused to open Outlook. The browser worked fine if you typed a URL in.
Two things were going on. The old router (BT Home Hub) had been happy to accept a DNS server the customer had once been told to use by a family member — 8.8.8.8 hard-coded into the adapter. The new router (a Smart Hub 2) forced DNS-over-HTTPS and quietly dropped anything else at port 53, so the PC could not resolve names and Windows flagged the probe as failing. Second, there was an old ExpressVPN adapter still installed from a Netflix workaround three years earlier — disconnected, but leaving a route in the table.
Set the adapter back to automatic DNS, uninstalled the dead VPN, ran ipconfig /flushdns, and the triangle went away inside a minute. Outlook re-authenticated on its own, Windows Update started downloading months of missed patches, and the phones kept working throughout because they had never been the problem. That is a very typical shape for this job across the East Lothian coast — and the same pattern we see when a VPN suddenly refuses to connect on a home network, only running the other way round.
When It Is Not the PC — It Is the Router
Occasionally the yellow triangle is telling the truth about the network, not just about the probe. Every device slows down at the same time, video calls stutter, and browsing works but feels laggy. That is a router-side problem — a WAN issue, an overheated hub in a warm cupboard, a firmware update mid-way through — and it needs the router looked at rather than the PC. That’s the case we describe in the guide to a router that keeps rebooting on its own, and it’s worth ruling out early with the ping-1.1.1.1 test above.
If two or more devices at once are showing connectivity warnings, treat it as a router or ISP problem. If only one is, treat it as that machine’s problem — even if it worked yesterday.
What To Do Right Now
- Confirm the network really works by reaching
1.1.1.1in a browser on the affected PC. Everything that follows depends on knowing whether the pipe is up. - Check DNS with
nslookup google.comin PowerShell. A clean lookup rules out the biggest single cause; a failed one points at DNS settings or a router filter. - Reset the adapter’s DNS to automatic under Network & Internet → adapter properties → IPv4 → “Obtain DNS server address automatically”. Fixes a surprising number of these on its own.
- Turn off the LAN proxy in Internet Options → Connections → LAN Settings, unless you actually run one on purpose.
- Uninstall any VPN client you don’t use and reboot. A dead VPN adapter is a routing landmine.
- If nothing has helped, reset the network stack: in an elevated PowerShell run
netsh winsock reset,netsh int ip reset,ipconfig /flushdns, then restart. It is more thorough than it looks and clears half the corner cases. - If it happened right after a new router and every other device is fine, the culprit is almost always something the old router tolerated and the new one does not. That is the point at which a same-day PC visit is faster than hunting through router menus on your own — and the same fix normally sorts a whole household of Windows machines at once.
- If you need a hand and the machine is otherwise healthy, remote support handles the Windows side without a callout. If the router itself needs adjusting we come out.
The through-line here is the one we keep coming back to on wired connections that mysteriously cap at 100 Mbps and every other “why only this one device” job: Windows is guessing about the network, and the guess is only as good as its inputs. Fix the inputs — DNS, proxy, adapter state, probe access — and the yellow triangle goes away because the underlying answer changes, not because you asked it to.
Short version: if one Windows PC insists there is no internet while every phone in the house says otherwise, it is almost never the router and almost always something on that one machine. It is a fifteen-minute job on the bench most days, and it doesn’t need a new hub.
Last updated: 8 September 2026