I don't know if you still facing this issue. I was also having your connection is not private error on chrome browser.
I would like to share few changes that I made after reading from other sources.
It may occurs due to SSL Certifications verification error i.e Expired SSL certificates (NET::ER_CERT_COMMON_NAME_INVALID) etc
To fix this check your system Date and Time is correct.
Change antivirus settings
Change firewall settings
These are few steps that you need to set properly to avoid this error.