Error messages:
error:14077438:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert internal error
error:14077410:SSL routines:SSL23_GET_SERVER_HELLO:sslv3 alert handshake failure
Reason:
Basically, this issue is caused because of an unsupported SSL version by cURL while trying to connect to HTTPS sites which support different SSL versions.
This issue is caused because IWP Admin Panel's server has an outdated version of cURL and OpenSSL.
Due to the recent SSLv3 vulnerability, a lot of sites have changed from SSLv3 to TLSv1 or v1.1 or v1.2.
So the sites with TLSv1.1 and TLSv1.2 can communicate with cURL version 7.39 or later and cURL should be using SSL via OpenSSL whose version should be 1.0.1c or later.
Solution:
Please contact the host of your IWP Admin Panel ask them to update the following
cURL version 7.39 or later (Minimum 7.34 should do, but 7.39 or later is recommended)
OpenSSL version 1.0.1c or later (If cURL is using SSL via OpenSSL, for any other SSL version please check this link http://curl.haxx.se/docs/ssl-compared.html)
If you are using Cloudflare please check the cloudflare FAQ on this issue https://support.cloudflare.com/hc/en-us/articles/204144518-SSL-FAQs (In this page please find the title "SSL on my free plan isn't working on an old OS/Browser" or cURL).
So if you want support existing cURL libraries you should use paid version of Cloudflare SSL.