Very Strange Network/Internet access problem

Lee · 19 Oct 2016 at 18:54

This one has me stumped. My dad's PC has all of a sudden stopped opening web pages and dropbox won't sync (message says "cannot establish a secure connection). It is connected to the network, and other devices on the home network have no issue. All devices (including router) have been rebooted. He can ping www.google.co.uk from command line, but from IE it will not open this or any other page. Malwarebytes has been able to connect online and update itself.

He's turned off Windows firewall, still the same.

Any ideas from anyone ?

Lee · 19 Oct 2016 at 19:10

Interestingly it won't allow a remote or local Teamviewer connection either.

tribz · 19 Oct 2016 at 19:58

Have a look at your date and time and check it's correct.

morfmedia · 19 Oct 2016 at 20:19

Often an Mtu issue

Try ping Google.co.uk -l 1400 if that times out investigate Mtu further

Lee · 19 Oct 2016 at 21:29

Thanks guys. Have checked date and time, all normal. Will get him to try the Mtu thing.

morfmedia · 20 Oct 2016 at 05:47

Forgot an important part of the command, do not fragment, thus run

Ping Google.co.uk -f -l 1400

Orcvader · 20 Oct 2016 at 11:35

Check the DNS server settings as well. Try changing to 8.8.8.8 and 8.8.4.4 and see if that helps.

What network adapter is it and what version of Windows?

K.C. Leblanc · 20 Oct 2016 at 16:28

Another thing is to look in Internet options to see if there's a proxy server set.

Steveocee · 20 Oct 2016 at 17:03

Any old anti virus sitting about? Disable them if so.

Techno_Viking · 20 Oct 2016 at 17:25

Check your firewall rules, he may have mistakenly blocked http port 80 traffic.

Lee · 21 Oct 2016 at 16:44

Thanks for the advice guys. He's brought someone in to fix it (rebuild in the end I think)

ChrisD. · 24 Oct 2016 at 14:45

Most likely an AV or firewall issue.