A couple days ago all of a sudden my laptop stopped connecting to the Internet. For instance, if I open the Chrome browser (64-bit version 78.0.3904.97) and enter in the url textbox:
then after a long wait the following message appears:
This site can't be reached
apple.stackexchangecom's server IP address could not be found.
Checking the proxy, firewall, and DNS configuration
This happens whether I connect with Ethernet or WiFi.
However, strangely, my VPN app (TorGuard v. 3.96.1) still manages to connect when turned on, and if I repeat the above scenario while the VPN app is on, Chrome downloads the apple.stackexchange.com front page.
Given the above error message, I should probably add that, as far as I know, I use no proxy or firewall, however if someone could explain to me how to check this definitively, I'll be grateful.
Computer: MacBook Pro (mid 2012)
OS: macOS Catalina, v. 10.15
It has been suggested that this question is a duplicate of this question. I don't think it is, becaused the other question says: "I just tried at a friend's house to check, with no problems." In my case I don't think trying to connect elsewhere would have solved the problem, because the problem was with the DNS settings, which, to the best of my understanding, are configured manually, and don't simply change by moving the device to another location (but I'm not sure).