A connection that opens some sites and refuses others is not half broken — it is giving you a precise clue. Total failures are line problems. Selective failures are name problems, and names mean DNS.
Partial failure feels random, but it follows rules. Big famous sites open instantly while a smaller site times out; your bank loads, a forum does not. Since some names resolve and some do not, the connection, the router and the line are all proven working in the same moment. What remains is per-name machinery: which resolver you asked, what it has cached, and whether the answer it gives — IPv4 or IPv6 — leads somewhere real. This page tests each suspect with one command, so the fix lands on the actual culprit instead of whichever setting you happened to change first.
Run the comparison in the panel: nslookup the failing site with your normal settings, then again with 8.8.8.8 added at the end to ask a public resolver directly. Two outcomes matter:
This single test prevents the most common misdiagnosis in this whole topic: blaming your PC for a stranger's broken name servers.
When a website changes hosting, its DNS records change — but resolvers keep the old answer until its TTL, its expiry timer, runs out. For hours, sometimes a day, one resolver sends you to the old, dead address while another already knows the new one. This is called propagation, and from the user's chair it looks exactly like a haunted connection.
Your honest options are two: wait for the cache to expire, or switch your DNS to a resolver that already has the fresh answer. Flushing your PC cache helps only if the stale copy lives on your PC — usually it lives on the resolver, which is why switching resolvers is the working move here.
Many sites publish two addresses: IPv4 and IPv6. Browsers prefer IPv6 when it is offered. If your network hands out IPv6 answers but the IPv6 path itself is broken — a router that half-supports it is the usual story — those sites hang or crawl while IPv4-only sites feel normal. Selective, confusing, and very common.
As a diagnostic, temporarily untick Internet Protocol Version 6 in the adapter properties and retest the failing sites. If they spring to life, you have proven the IPv6 path is the fault. The proper fix is at the router or ISP; leaving IPv6 off on one home PC is an acceptable workaround, but label it honestly as one, and revisit it rather than forgetting it.
If the failing sites work in another browser or in apps, the network has already been acquitted — the remaining suspect lives in the first browser. Modern browsers can use DNS over HTTPS, their own private name-resolution channel, which ignores your Windows and router settings entirely. A bad setting or a failing DoH provider then breaks selected sites in that browser alone.
There is a dedicated page in this series on the secure DNS setting. Short version: find it in the browser's security settings, set it to use your current provider or turn it off for the test, and retest before touching Windows again.
Notice what is not on the list: reinstalling the browser, resetting Windows, replacing the router. Selective failure is information-rich; five minutes of testing spends it wisely.
See every step on a real Windows PC — the tests, the commands and the DNS change, in order.
▶️ Watch Full VideoRun nslookup for that name against your resolver and against 8.8.8.8. If both fail, the site's own DNS is broken and the repair is theirs. If only yours fails, switch resolver — your assigned server is holding a bad answer for that name.
The pattern is still most likely resolver caching or the bank's own DNS change, not an attack on you personally. Verify through the bank's official app on mobile data, and never enter credentials through a page you reached after strange redirects — if the address bar shows an unexpected name, stop and use the app instead.
Rarely. Browser cache stores page content, not name answers. The caches that matter here are your PC's DNS cache — cleared with ipconfig /flushdns — and your resolver's cache, which you cannot clear at all; you can only wait or switch resolvers.