Guided check
0/4 checkedMatch the symptom, then work through the safe checks.
1. What best matches what you observe?
2. Complete only the checks that are safe for you.
4 user-level checks are available in this guide.Stop immediately if any warning condition applies.
Show stop conditions
- Certificate warnings appear for many trusted sites
- The network is managed and filtering is intentional
Likely causes
- A DNS resolver returns incomplete or blocked results
- IPv6 or routing is broken on part of the path
- VPN, parental control, security filter, or browser extension blocks selected domains
- Incorrect date and time causes certificate failures
Quick checks, in order
Try the same sites on another device and network
Compare Wi-Fi with mobile data.
Check the exact browser error
DNS, timeout, certificate, and blocked messages point to different causes.
Disable VPN or filtering for one controlled test
Do not bypass organization or parental policy without authorization.
Restart router and verify date and time
Avoid random MTU or registry changes before evidence.
Which pattern matches the failures?
Same sites fail on every device
Router DNS, filtering, provider routing, or the sites themselves are likely.
Only one browser fails
Extensions, secure DNS, proxy, cache, or security settings are likely.
Sites work on mobile data
The home router, DNS, provider, or local filtering path is likely.
Stop and get qualified help when
Do not continue troubleshooting if any of these apply:
- Certificate warnings appear for many trusted sites
- The network is managed and filtering is intentional
Frequently asked questions
Can DNS affect only some websites?
Yes. Failed or filtered name resolution can affect selected domains while cached or reachable sites still work.
Why do apps work when websites fail?
Apps may use different servers, DNS behavior, protocols, or cached sessions.
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