I’ve recently been out to two iMacs with networking issues where they connected fine to WiFi or network cable as far as the Mac thinks but then nothing works. Additionally, my Windows computer sometimes forgets it’s connected to the Internet, even though the network cable and the router is fine. Let’s investigate…
Mac networking is quite a simple system, because the Mac OS system is designed to have easy features for all users.
3rd party antivirus and VPN programs install their code into this Network system and interfere with the behaviour of the Network system to prevent hackers from hacking into your computer but when the Mac OS is updated, these programs malfunction and prevent the Mac from accessing the Internet.
In order to fix this problem, you have to click on each 3rd Party Network extension and press the – symbol to remove them.
3rd party programs can change the DNS settings, and when the DNS settings are configured to a server your Mac can no longer reach (because the 3rd party extension is broken) so you can add new DNS entries with the + button.
Google’s DNS is 220.127.116.11 and 18.104.22.168 but if you want to use the more secure Quad9 DNS, then use 22.214.171.124
Occasionally, Microsoft Windows forgets how to do the Internet. When it does this out of the blue rather than restart the computer, which will fix the problem, you can disable the network connection and then enable it and it fixes itself.
This method is especially useful if you are doing something and you don’t want to have to save everything or have to redo a complicated website because you have to reboot.