I have been working for quite some time on a website that highly depends on Paypal working properly on it. Without it, it is really useless.
Around 1 in the morning
I've had the same problem.
My server is an old version of Ubuntu 12.04
Check sertificates
echo "All certificates in ca-certificates.crt, listed by subject, check for presence of VeriSign's 'Class 3 Public Primary - G5':"
awk -v cmd='openssl x509 -noout -subject' '/BEGIN/{close(cmd)};{print | cmd}' < /etc/ssl/certs/ca-certificates.crt | grep "G5"
I updated openssl.
sudo apt-get install openssl
I could updated curl only by this instruction. http://pavelpolyakov.com/2014/11/17/updating-php-curl-on-ubuntu/ curl 7.47.1 version
And I updated libcurl. http://juniway.blogspot.com/2015/12/curl-48-unknown-option-was-passed-in-to.html