Facebook API - timed out before SSL handshake - facebook

Question

I'm facing this issue with the Facebook PHP SDK. My application is hosted on AWS EC2 (Virginia).
It's randomly happening but has recently increased. I've read that it was necessary to specified some cURL options, so I've done so:
self::$CURL_OPTS[CURLOPT_IPRESOLVE] = CURL_IPRESOLVE_V4;
self::$CURL_OPTS[CURLOPT_SSLVERSION] = 3;
self::$CURL_OPTS[CURLOPT_CONNECTTIMEOUT] = 20;
Because IPv6 is not supported on EC2 instance, we need to force IPv4
I've read to force SSL version 3
I've tried to increase the timeout from 10 to 20 seconds
I'm still getting the following error:
FacebookAPIException: timed out before SSL handshake
Which I believe is not a Facebook exception but a cURL exception.
I can't really enable the verbose mode because I have many requests and just a small percentage is failing at the moment.
Anyone is having the same issue?
My system:
Centos Linux 2.6.32-431.5.1.el6.x86_64 #1 SMP Wed Feb 12 00:41:43 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
libcurl.x86_64 7.19.7-37.el6_4
php curl
cURL support => enabled
cURL Information => 7.19.7
...
Protocols => tftp, ftp, telnet, dict, ldap, ldaps, http, file, https, ftps, scp, sftp
Host => x86_64-redhat-linux-gnu
SSL Version => NSS/3.14.0.0
ZLib Version => 1.2.3
libSSH Version => libssh2/1.4.2
UPDATE
I've opened a Facebook bug here: https://developers.facebook.com/x/bugs/1461144600769806/
UPDATE 2
My facebook bug has been closed without any useful answer.
I've managed to log the verbose debug of cURL for this error:
Verbose log:
* About to connect() to graph.facebook.com port 443 (#0)
* Trying 173.252.100.27... * connected
* Connected to graph.facebook.com (173.252.100.27) port 443 (#0)
* Initializing NSS with certpath: sql:/etc/pki/nssdb
* CAfile: /etc/pki/tls/certs/ca-bundle.crt
CApath: none
* timed out before SSL handshake
* NSS error -5978
* Closing connection #0
On success cURL is doing the following:
Verbose log:
* About to connect() to graph.facebook.com port 443 (#0)
* Trying 173.252.112.23... * connected
* Connected to graph.facebook.com (173.252.112.23) port 443 (#0)
* Initializing NSS with certpath: sql:/etc/pki/nssdb
* CAfile: /etc/pki/tls/certs/ca-bundle.crt
CApath: none
* SSL connection using SSL_RSA_WITH_RC4_128_SHA
* Server certificate:
* subject: CN=*.facebook.com,O="Facebook, Inc.",L=Palo Alto,ST=California,C=US
* start date: Oct 28 00:00:00 2013 GMT
* expire date: Aug 05 23:59:59 2015 GMT
* common name: *.facebook.com
* issuer: CN=VeriSign Class 3 Secure Server CA - G3,OU=Terms of use at https://www.verisign.com/rpa (c)10,OU=VeriSign Trust Network,O="VeriSign, Inc.",C=US
> POST /xxxxxxxxxxx/feed HTTP/1.1
User-Agent: facebook-php-3.2
Host: graph.facebook.com
Accept: */*
Content-Length: 244
Content-Type: application/x-www-form-urlencoded
Errors happen randomly. So is it coming from Facebook of from my server?