These thin clients ship with few Trusted Root Certificate Authorities. You may find, as I did, that the provider of your SSL certificate is not one of them. Even if it is as recognizable as DigiCert. So now you need to add it.
There are three main ways to accomplish this. You can use a USB drive, an FTP server, or configure it with your centralized configuration via the INI file.
For initial testing, you will probably opt for one of the first two. A USB or FTP install is the easiest way to set one or a couple up to connect. All you need is the intermediate and root certificate for your certificate.
Just drop the files on the root of the USB or FTP, Now you can go into the System Tools/Certificates and import (choosing the source from the drop down).
However, this is not a solution for a large thin client population. If you use more than a few of these things, you are probably well versed in the WNOS.INI file parameters. This is hosted via FTP so that on every boot of the thin client, the settings are synced. So in theory we can set this up and just boot up the thin client to install, and, for once, it really is that easy.
First thing you need to do is create a cacerts subfolder in your WNOS folder. The end result should be something like this:
As you have probably guessed this is where you drop your Certificate Authority (and intermediate) certificates.
Now, open your WNOS.INI file and add line for each certificate:
AddCertificate=intermediate.crt AddCertificate=certificateAuthority.crt AddCertificate=domainCA.cer
Those are the three required for my environment.
Hope that helps someone else.