Certain webpage fail

Try setting up another admin user account to see if the same problem continues. Please post back on whether or not this worked. Also try the Safe Mode. Please post back on whether or not this worked.

Isolating an issue by using another user account 

Safe Mode - About

If it works in the Safe Mode, try running this program when booted normally and then copy and paste the output in a reply. The program was created by Etresoft, a frequent contributor.  Please use copy and paste as screen shots can be hard to read. Click “Share Report” button in the toolbar, select “Copy to Clipboard” and then paste into a reply. This will show what is running on your computer. No personal information is shown.

Etrecheck – System Information

If the log won’t post, try posting it in Pastebin and provide a link in a reply        Pastebin

1. Power off the router. Unplug it from the wall. Wait a while.

    Plug it back in. Power the router on. Wait until all lights are lit properly. It will take a while.

    Restart the computer.

    Start up in Safe Mode.    https://support.apple.com/en-us/HT201262    

    Launch Safari and test the website.

    Once in Safe Mode, click the “Restart” button at the bottom to exit Safe Mode.

  2.  If you can’t open a website in Safari on Mac