I keep getting the message "Safari can't find the server."

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

Try setting up another admin user account in System Preferences/Users & Groups 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. 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

willymoo Said:

“I keep getting the message "Safari can't find the server." I've never had trouble getting into Safari and wonder if anyone has a solution.”

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Temporary Internet Files (Cookies & Cache): Clear your Temporary Internet Files. Cookies perform remembrance of site-entered data. Cache keeps a snapshot of the last time your visited a site.

So, clear them.

Use this Link: Clearing History and Cache - Apple Communities

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

Did you try another admin account or the Safe Mode?

willymoo Said:

”Still not working.”

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Safari Needs to Completely be Reset:

If Safari stopped working, then remove it from the macOS. Once removed, reinstall the macOS.

Go Here: Safari Passwords Locked

Perform this answer as both prompted and shown. Safari would be reinstalled; nothing would be lost.