Certain websites won't open in any browser, others do

[Atyilu]

Windows version related : Windows 10 Home, Version 22H2 - build nr: 19045.4291

Hardware: Dell Latitude E6540 laptop

Please help me find out how to rectify the faulty operation as desbribed below :

Problem statement:
Certain websites won't load in any browser ( Chrome, Ms Edge, Opera , .... ) These sites, however,
- could be opened seamlessly in the past on the laptop in subject;
- can now be opened properly on all other computers, smart phones using the same local network ( same router )

Examples: The following sites are blocked consequently :
- Expert Microsoft Help, with all of the Microsoft Applications from Excel programming, Access training to our free Microsoft VBA Forums ,
- REINER SCT - en - Chipkartenleser für sicheres Onlinebanking, Zeiterfassung, Zutrittskontrolle und Personalverwaltung,
- Kártyaolvasó - e-személyi olvasó, RFID chipkártyaolvasó, webshop, vásárlás hivatalos magyarországi forgalmazótól ,
- Link Removed,
- Medtronic

(Note: for some reason this field here shows site description rather than the URL I entered )
Those URLs fail to show content in a consequent manner: the ones that get blocked once, will get blocked all the time, whereas all other websites that once open properly , will get loaded any other time.

The websites that won't load demonstrate a circled "i" symbol at the address bar, pls see attachment for illustration

It is irrelevant from this aspect whether the websites use http://or https://protocol, the faulty or proper behaviour is independent from that protocol.

In addition:
- installed applications like Spotify do not get connected to the server, the app's user interface remains idle.
- Ms Outlook mail client fails to send messages, they get stuck in.


What I tried so far to avert it:


Windows device manager : Network adapter drivers checked for updates: all are up-to-date

Switched the router off and back on. ( 200 Mbit/s broadband connection confirmed )

made a hard reset of the modem/router

disabled, then enabled network adapter drivers ( see attachment)

cmd --> ipconfig /flushdns , ipconfig /renew , .......

cleared the cache of the browsers

checked router configuration: OK

checked if any url is set to be blocked: none

Checked MS Defender firewall: no blocking set ( currently no other firewall is installed )

disabled browser extensions

It is highly possible, that the root cause is to be found somewhere around certificate management,


Thank you for your time and efforts.

 

[ChatGPT]

Your detailed report certainly suggests multiple troubleshooting steps that you've undertaken which gives me a good understanding of what you've tried so far. You're right to deduce that your issue might be attributable to certificate management or DNS issues. Here are some additional steps I recommend: Reset Winsock and TCP/IP: Winsock settings contain your computer's network configuration settings and resetting them might solve your issue.

1. Open Command Prompt as an administrator.
2. Type the following commands and press 'Enter' after each:

   netsh winsock reset netsh int ip reset

3. Restart your machine to let the changes take effect. Change your DNS Server: Sometimes, your ISP-provided DNS servers might have issues resolving specific websites. Changing your DNS server to a more universally recognized one like Google's might help.
4. Open Control Panel > Network and Sharing Center > Change adapter settings.
5. Right-click on the connection you're using and click on 'Properties'.
6. Select 'Internet Protocol Version 4 (TCP/IPv4)' and click 'Properties'.
7. Choose the 'Use the following DNS server addresses' option.
8. Input 8.8.8.8 in 'Preferred DNS server' and 8.8.4.4 in 'Alternate DNS server'.
9. Click 'OK' and check if your issue is resolved. Verify your Hosts File: This file is used by your operating system to map hostnames to IP addresses. If this file is modified (usually by malicious software) it can lead to certain websites being blocked.
10. Navigate to 'C:\Windows\System32\drivers\etc\hosts' and open the 'hosts' file with Notepad.
11. If you spot any suspicious entries or the URLs of the websites that you're unable to access, delete those lines.
12. Save and close the file. Check for Malware and Malicious Programs: Malicious programs often modify your network settings to block certain websites. Using a trusted anti-malware software, perform a thorough scan of your system and remove any detected threats. Reset your Browsers: Sometimes, the issue might lie within your browsers' settings.
13. In each browser, go to the browser settings or options and look for an option to 'reset settings'.
14. Note that this will delete any saved bookmarks, passwords and other user data, so ensure you have a backup before proceeding. Remember to restart your computer after performing each of the steps. If the issue persists, consider seeking the help of a professional or support from your ISP, especially if you receive certificate errors when trying to access those websites. Hope this helps!

 

[Neemobeer]

Since the issue is only present on a specific system and specific sites somethings to check.
Hosts file for site entries
Browser extensions that can interfere
Security software that includes web filtering
If you have any hardware security devices with specific blocks in place your the problematic device

 

[Atyilu]

Thanks gentlemen,

All these steps have been executed. No improvement seen.

Got no third-party antivirus, or firewall. Only MS integrated Defender software is running. No virus found either after offline, or online search.

DNS provider has been changed accordingly.

Browser has been uninstalled and reinstalled.

No webfiltering set in the router either.

Please help me evaluate the content of the host file. To me it seem to be empty. Is that normal ? See attachment.


Recently I've installed and uninstalled a driver for a smart card reader equipment, called Cyberjack. ( reiner-sct.com )
It manages and handles certificates, makes authentication, electronic signatures possíble. The manufacturer denies any relevance between the driver and the a.m. technical issue.
Do you think that certificate management can cause such malfunction in internet access ?

 

[Neemobeer]

Your hosts file has the defaults so nothing there.

If you want you can download a copy of wireshark and send the pcap file that will tell what's happeing at the network level.

1. Download and install wireshark
2. Open your browser to a blank page
3. Start wireshark
4. Open a powershell prompt and type Clear-DNSClientCache
5. Back in wireshark select your network interface to capture, the active interface will have a little traffic graph
6. Back in the browser browse to a problematic site
7. Once you get the error go back to wireshark and click the stop button red square
8. File save as pcap or pcapng
9. Upload/share that file

 

[Atyilu]

Thanks Neemobeer,

That's what I have done. (I am fortunate enough, that Wireshark.org belongs to those sites, which load properly, not like many other URLs.) Huhhh....

Actually I find two items where traffic sign is associated with on the WS user interface. ( see attachment)
So I executed these steps for both active interfaces, if at all both are interfaces.

Are the contents in the attachments informative enough to detect the underlying cause ?

Edit : ... Just realized that Windowsforum does not allow me to attach the .pcap , pcapng files, those fail to show up in my post. As a workaround let me attempt to add a screenshot of the .pcap files instead.

Other than that, it raises my eyebrow on the ipconfig /all results, that the "Autoconfiguration IPv4 Address. . : 169.254.144.36(Preferred)" is unusual to me. It always used to be set automatically to 192.168.0.1 so far.
now it's different. Can that be considered as normal ?
(anyway, neither of the above router URLs load, both return the error in subject of this thread. )

 

[Neemobeer]

You'll need to zip the pcap, or throw it in online storage and link to it. Also, you'll want to capture on the interface called 'Wi-Fi'

 

[Neemobeer]

A 169. address is an issue, that would mean your device isn't getting an address from DHCP for IPv4. However, you do have a valid IPv6 address so it's likely using that

 

[Neemobeer]

Ahh I think I know what your issue is. So not all websites are compatible with IPv6. lastpass.com is not, but wireshark.org is. You can confirm here IPv6 Compatibility Checker - Check if a Domain Supports IPv6

So the question is why don't you have an IPv4 address and also do you not have one externally? Search for "what is my ip" and see if you get only IPv6 or if you have an IPv4 address

 

[Atyilu]

Thanks Neemobeer,

- Attached you'll find the zipped versions of Wireshark's .pcapng results, as well as a cbs.log file.

- Whatismyip.com returned the result as depicted on the attached screenshot. :
public IPv4 --> Not detected.
public IPv6 --> listed

Is it vitally important for the computer to have an IPv4 address assigned ?

- (Edited ) : DNSchecker.org confirmed, that
> most sites which load properly ARE indeed IPv6 compatible ( kurier.at, index.hu, idokep.hu, youtube.com, ... ( an exception is https:// carelink.minimed. com ) ), whereas
> sites, which do not load at all, are NOT IPv6 compatible.


So the questions filter down to: how can I restore the former configuration which used to allow me to access URLs not having IPv6 compatibility ?

 

[Neemobeer]

You'll need to make sure it's configured on your router

 

[Atyilu]

Thanks Neemobeer,

in the meantime the configuration error has been resolved.

Internet Settings -> Properties - > Restore advanced settings ( refer to attachment )

This button press has immediately remedied misconfiguration of IPv4 settings, so also the only IPv4-compatible websites are back again.

If you have an idea why this could cure the temporary desease of the network I would appreciate your expert explanation.

 

[Neemobeer]

I don't know that it's fully documented what all that option resets, but it does reset the network components per network adapter. We won't know what it was previously configured to, but it's possible DHCP was mis-configured on your adapter. Technically anything can programmatically change these settings.

 

[Atyilu]

Thanks.

I'm just an ordinary layman, so this question may sound stupid: Are DHCP settings to be configured for each computer connected to a LAN, or once you configure DHCP on the router's user interface, that will affect all computers on that particular LAN ?

 

[ChatGPT]

Nice summary — those fixes you tried are exactly the right starters. If you want a compact, reliable checklist you can run now (and a low‑effort diagnostic I can parse if it still fails), try the steps below. I’ll explain what each step proves and include the exact commands to paste into an elevated Command Prompt / PowerShell.
Quick checks & fixes to try now (5–10 minutes)
1) Flush DNS and restart the DNS client

• Commands (Admin CMD/PowerShell):
  ipconfig /flushdns
  sc stop dnscache
  sc start dnscache
  What it tells you: clears stale DNS entries and restarts the Windows DNS client service. If sites immediately return, DNS cache was likely the cause.

2) Reset Winsock / TCP‑IP and reboot

• Commands (Admin CMD):
  netsh winsock reset
  netsh int ip reset
  ipconfig /flushdns
  shutdown /r /t 5
  What it fixes: corrupted LSPs / network stack issues that let some apps fail while basic networking (ping/nslookup) still works. Reboot is required.

3) Check which DNS your adapter is actually using

• Command (Admin PowerShell):
  Get-DnsClientServerAddress -AddressFamily IPv4
  or use ipconfig /all
  If DNS shows 127.0.0.1 (or another local address) your machine is using a local resolver/agent (Pi‑hole, WARP, VPN DNS) that may be broken — uninstall or reconfigure that agent. fileciteturn1file2turn1file16

4) Check and reset WinHTTP proxy + system proxy

• Commands:
  netsh winhttp show proxy
  netsh winhttp reset proxy
  (also check Settings → Network & Internet → Proxy and ensure no manual proxy is set)
  Why: WinHTTP/WinINet proxies or leftover proxy environment variables can break browsers/apps even when DNS/ping works. fileciteturn1file1turn1file8

5) Inspect hosts file and browser state

• Hosts file path: C:\Windows\System32\drivers\etc\hosts — open with Notepad (Run as Admin). Remove any lines redirecting domains you need.
• Reset/refresh browser: Chrome: chrome://settings/reset → “Restore settings to their original defaults.” Edge/Firefox have similar “Refresh/Reset” flows.
  These catch cases where local redirects, extensions, or corrupted browser state block specific sites.

Check for VPN / security / DNS‑filtering software

• Many users find Cloudflare WARP, Proton VPN, corporate VPN clients, or security suites leave a kernel‑level network filter or a local DNS resolver that blocks only some domains. If you have any of these, fully uninstall (not just “turn off”) and remove any TAP/Tun adapters in Device Manager, then reboot. fileciteturn1file4turn1file8

More diagnostic checks (if quick fixes don’t help)

• Test DNS via public server: nslookup google.com 8.8.8.8
• Test HTTP by IP vs name (PowerShell, Admin):
  Try { (Invoke-WebRequest 'http://216.58.214.14' -UseBasicParsing -TimeoutSec 8).StatusCode } Catch { $.Exception.Message }
  Try { (Invoke-WebRequest 'Google' -UseBasicParsing -TimeoutSec 8).StatusCode } Catch { $.Exception.Message }
  Interpretation: If the IP-based request succeeds but the name-based one fails, that points at DNS/proxy/WinHTTP or a local DNS agent.

If you prefer I collect everything for you (one file you can upload)

• I can give you a tiny script to save to C:\Temp\run_diag.cmd, run as Admin, and it will create C:\Temp\webdiag.txt with ipconfig /all, Get‑DnsClientServerAddress, netsh winhttp show proxy, sc query dnscache, Invoke‑WebRequest outputs, routing, and more. Copy that file to a USB or take a photo and upload here — I’ll read it and give the exact next step. Say “create diag file” and I’ll paste the batch to save. fileciteturn1file0turn1file2

Two important safety notes

• If you uninstall security or VPN software temporarily to test, reinstall it afterwards or make sure you understand the security tradeoff while it’s absent.
• The Winsock/TCP/IP reset requires a reboot and will remove some network customizations (Wi‑Fi profiles saved by Windows remain, but some drivers will be reinstalled).

Which do you want to do now?

• I’ll stay with you while you run the quick commands (I can tell you exactly which to paste), or
• I can paste the one diagnostic batch file for you to save/run and then upload the resulting file/photo.

Tell me which option and whether you’re on Wi‑Fi or Ethernet (and if you use any VPN/security tools).