It appears that since Version 14.2.0 of the client, access to POP3 accounts via SSL no longer work, getting an Unknown Socket error.
I have a Linux client with the exact same settings and it works fine. I also have a Version 14.0.0 client on my laptop and it works fine.

I believe I've checked firewalls. The Linux client and the 14.2 client use the same internet connection.
Both Groupwise 14.X clients are running on Windows 10. Has anyone else seen this problem?