Safari and Chrome cannot establish a secure connection to websites. What do I do?
For the past week or so neither Safari nor Chrome is able to open certain websites. For example, if I type in 'yahoo.com' or 'photos.google.com' in the address bar, it tries loading the page for a few seconds and then shows the error: 'Safari can't open the page' or 'This site can't be reached' (in Chrome). The reason given by the browsers is that it either can't establish a secure connection or the connection timed out. Sometimes it can't load a page because "the server where the page is located isn't responding".
Another thing I'd like to mention is that I changed my Firewall Options recently. While changing that I did remove two services from the list shown in the Firewall Options pane. I only remember that they were services run by Apple apps/software. Just thought I'd mention it in case that had anything to do with my issue.
I'm using a mid-2014, 13-inch MacBook Pro that runs macOS 10.13.4 (High Sierra; Build: 17E202) and Safari 11.1.
*My proxy setting is set to automatic.
MacBook Pro with Retina display, macOS High Sierra (10.13.4), null