SSL constantly changes so you need to keep your software current.
For example SNI support, which allows a single servers to have multiple domain names, was added in PxPlus 14. Many earlier ciphers are often blocked due to security issues thus unless you use newer ciphers the host will not connect. Also, each release of PxPlus includes newer Trusted certificate files (ca-bundle.crt) which you need to update as all certificates, even those of high level trusted suppliers, have expiry dates.
Try using a new version of PxPlus to see if it connects, if so you may need to upgrade. V13 is no longer supported.