curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to domain.com:443
First check your network path using
curl -V URL
The URL may be your proxy setting and see what response you are getting.
If you are getting the proper output without the error then it is your SSL certificate issue.
The SSL error is not supporting your default SSL or the server is using ciphers that are no longer considered secure; ciphers based on 3DES and RC4. The default ciphers in the ssl library do not include these ciphers for security reasons.
To add support for these ciphers, you can manually set the default cipher Suite. The next line sets DES-CBC3-SHA as the proposed cipher.
curl --cipher DES-CBC3-SHA <your parameters>
Use –cipher ALL
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