fatal: unable to access 'https://github.com/xxx': OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to github.com:443

If you are behind a proxy, try the following:

git config --global --add remote.origin.proxy ""

After reinstalling Git did nothing, I found an issue on GitHub that helped me solve it.

In your terminal run this command first:

git config --global http.sslBackend "openssl"

Then this one:

git config --global http.sslCAInfo "C:\Program Files\Git\mingw64\ssl\cert.pem"

You may need to change your path depending on where you have it installed.

Opening a new terminal session worked for me