Safari can’t open the page

The article posted in the thread is for Mac OS Yosemite , your profile shows using as Mac OS Catalina 10.15.

The network settings are weak and Mac can't connect to it Troubleshoot connecting your Mac to the internet - Apple Support

Recommended settings for Wi-Fi routers and access points - Apple Support

Troubleshoot external networking devices on Mac - Apple Support

If you can’t open a Safari window on Mac - Apple Support

Also you might be using anti virus , cleaners , softwares on the Mac if so uninstall all of them .

If you have any anti-virus software installed, disable/remove it and test.

Try suggestion given here.

https://support.apple.com/en-us/HT204937