safari browser goes to can not reach page every time

1. Power down 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.

 2. Start up in Safe Mode. This will remove some system caches.

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

    https://support.apple.com/en-us/HT201262

     Launch Safari holding the shift key down. This will start Safari in Safe Mode

Are you running any anti - virus programs? Using a VPN?

You can also try setting up another admin user account in System Preferences/Users & Groups to see if the same problem continues.

Isolating an issue by using another user account 

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. If the log won’t post, try posting it in Pastebin and provide a link in a reply. After pasting the report in a PasteBin page, go to the top of the page, and copy the address in the URL bar. Paste that in a new reply.        Pastebin

Etrecheck – System Information

Web site version if required.  https://etrecheck.com