The error you see "Network Error - The application experienced an internal error loading the SSL libraries.[12157]"
Is this happening only to one of the VPN users?
Can you do the following :
a. Check the CERT on the CAS and CAM. If using IP, make sure the IP are correct. Check out that the DNS records. Regen the CERT and reboot.
b. Check the timezone. If using FQDN, make sure they can resolve via DNS.
c. On the client accessing, it needs to be 128bit SSL - make sure the client has high encryption on browers.