Browsers Suddenly Can't Connect To Internet

Jamis · Sep 17, 2025

This morning, FireFox & Chrome suddenly can't connect to the internet with the PC. I ran CCleaner, have power cycled the modem and router, restarted the PC, checked updates (paused until 10/01), ran Norton360 scans to no avail. PC shows the internet connection is good and secure, but the browsers won't connect. All other devices on our network connect just fine and the browsers on those devices work perfectly. I am stumped.

glasskuter · Sep 17, 2025

Have you restarted?

Things to try:
.Run network troubleshooter. Settings>System>troubleshoot>other troubleshooters>Network & Internet>-RUN

reset adapter Reset Network Adapters in Windows 11

Attached is @FreeBooter .bat file which resets network components. RIGHT click on the .bat file and select run as administrator.

Jamis · Sep 17, 2025

I should add that the PC was powered off all night and powered on at about 8:30AM. After booting up, I launched FireFox which opened to the CNN home page and I opened a second tab to the ISP's e-mail server. Both opened successfully with no issues. The PC sat unused until about two hours later, when the problem cropped up. The only thing I can see is there were updates to the Defender Antivirus software on 09/16/2025. Unfortunately, I don't see any way to remove them. I suppose I could restore the last Macrium Reflect Image from 09/07/2025. The PC is directly connected to the ISP modem/router via the ethernet ports.

Jamis · Sep 17, 2025

glasskuter said:
Have you restarted?

Things to try:
.Run network troubleshooter. Settings>System>troubleshoot>other troubleshooters>Network & Internet>-RUN

reset adapter Reset Network Adapters in Windows 11

Attached is @FreeBooter .bat file which resets network components. RIGHT click on the .bat file and select run as administrator.

Yes, restarted the PC, and the modem/router a couple of times. Troubleshooter had found nothing as well as Norton's network scan. The RNA link fixed the issue. I will remember it if it happens again. I still have no idea what caused the problem, but it's fixed. Thanks so much for the help.

Jamis · Sep 18, 2025

OK, the problem returned. It is only caused by the ISP's email website on both FireFox and Chrome. Once you log into the site and try to use it, the browser connection to the internet fails. The system shows the internet connection is good and everything else in the house works on the internet. All other URLs work just fine on this system, even if left idle for awhile. I went to one of the ISP's offices and they were able to log into the mail web page with my userid and password on a windows PC with no issues. So the problem is on this machine. I have no idea what to check as the Windows trouble shooting finds no issues and neither does Norton360. I have a Macrium Reflect system image from 09/07/25, as well as others prior to that. Thinking a restore might correct things. Is there any way to remove Windows Defender updates since they are a daily update? The website works just fine using FireFox on an iPad, so the issue is with the W11 PC.

glasskuter · Sep 18, 2025

Clear cookies and cache in both browsers.
If that doesn't work clear dns cache. Click the Start menu and type "cmd." Right-click on the Command Prompt and choose Run as Administrator. Type ipconfig /flushdns

Jamis · Sep 18, 2025

glasskuter said:
Clear cookies and cache in both browsers.
If that doesn't work clear dns cache. Click the Start menu and type "cmd." Right-click on the Command Prompt and choose Run as Administrator. Type ipconfig /flushdns

We always clear browser cookies and cache after each use. Ran ipconfig successfully. No change. The browser internet connection still fails after successfully signing in to the web site. The only change to the system is a Windows Defender update on 09/17/25 when the problem started, but there is no way to remove individual Defender definitions.

glasskuter · Sep 18, 2025

Disable all browser add-ons and test.
See if it happens using EDGE normally. Then test using Edge Internet explorer mode. (edge>click 3 dots "reload in Internet explorer mode")

If Edge fails as well, Since you are getting to the site and successfully logging into it before the connection to the site drops I would be looking toward the isp.
Them logging into the site successfully from their office using your credentials is not the same as you logging in through your end to end connection path.

Jamis · Sep 18, 2025

The only browser add-on is AddBlockPlus and the problem continues with it disabled. Edge works fine in both modes with no add-ons. I went to one of the ISP's branch offices, so we were using their broadband network there just like we do at home. Since this website works via FireFox on iOS devices, I'm thinking the problem is with the version of FF for Windows11. Don't know how to back date FF. Still considering doing a MR recovery.

Jamis · Sep 18, 2025

Scratch the thought about it being just FF, Chrome still does it also. There is something damaged in the PC's software, just don't know where to look.

Jamis · Sep 19, 2025

Workaround is to use Edge Chromium for the ISP's web mail site. Works fine all day with no issues. Going to hold off doing the MR system image restore. The problem could be rooted in an update from Microsoft, HP, FireFox, Realtek, or some combination of them. Way too many finger pointing possibilities to wrestle with righ now.

retexan599 · Sep 20, 2025

I have been having a similar problem intermittently:

Intermittent Inability to Connect to Websites

Have been seeing problems connecting to various websites. It comes and goes. Can fix temporarily by restarting, but that can be awkward. Not all sites will fail at same time. Do not see this problem on my iPad. Sometimes the problem fixes itself; sites stop connecting, then later will connect...

www.elevenforum.com

Sometimes, this works:

Fix Wi-Fi connection issues in Windows - Microsoft Support

Learn about different things you can try to fix network connection problems in Windows.

support.microsoft.com

Sometimes it doesn't

TairikuOkami · Sep 20, 2025

retexan599 said:
Sometimes, this works:

Disabling all the nonsense might work, it sure made my connections stable.
Especially dumb IPv6, I disable all protocols except IPv4, setup static IP/DNS.

https://www.elevenforum.com/account/th-attachment-manager/111704/view

retiredat44 · Sep 20, 2025

don't just disabled browser addons, delete them, remove them... you can always put them back..

Jamis · Sep 20, 2025

Ran WU today to install the September "B" updates (4 updates, HP, windows net, "B", & MSRT), but it didn't change the problem occurrence. Waiting for the ISP's response for modem/router firmware update.

I think I failed to mention that the PC is connected to the ISP's modem/router via the ethernet ports.

retiredat44 · Sep 20, 2025

I just saw you use Norton!.. i removed and stopped using Norton because their software caused the same issue, so I dumped them totally and have not had any problems since. remove Norton! Win Defender will work fine. Norton started enabling VPN and wrecked my network... that was the last straw!

Jamis · Sep 22, 2025

retiredat44 said:
I just saw you use Norton!.. i removed and stopped using Norton because their software caused the same issue, so I dumped them totally and have not had any problems since. remove Norton! Win Defender will work fine. Norton started enabling VPN and wrecked my network... that was the last straw!

Thanks, I'll look at that. Just finished working with the ISP tech folks on their supported router (I own it, but they support it). They have had some network issues this last week. They would just reboot the modem/router when they encounter a problem. It would go unnoticed, except our security system would call it out. At least I know the modem firmware is working properly.

retiredat44 · Sep 23, 2025

don't hesitate, remove it!

Jamis · Sep 23, 2025

I disabled the Norton360 functions with no change. I then uninstalled Norton360 with no change to to problem. In the meantime, FireFox updated the browser from v.140.0 to v.140.0.1 and the problem has changed to where it now takes longer for the browser to break its internet connection with the ISP's mail client web site, and requires a network reset in W11 to get FireFox working again. The web site email client is supplied by a third party, so I'm not expecting any real fix coming anytime soon. It appears that this web site, the FireFox browser, and W11 combined cause the problem. The problem does not exist using Edge to access the email web site, so that's what we'll use. FireFox works just fine on any other URL.

XxXxX · Sep 23, 2025

have you tried to add your own DNS server addresses.
settings > network > 'your network connection' WiFi or Ethernet

then add DNS addresses.
IPv4
1.1.1.1
primary

IPv4
1.0.0.1
secondary

leave the IPv6 addressing as auto for the time being.

save the settings
then see if your system can connect to the internet.
best of luck, Steve ..

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