SSL/TLS Certificate

I need the help of some smart Wilders Security Forum members to help me better understand and figure out something. I have a D-Link DNS-343 NAS that has FTP capabilities. I recently made the change to allow only secure FTP connections. It's taken some serious figuring out on my part due to my lack of understanding combined with D-Link's famous lack of support. However, I have it working now. Here's the issue:

Upon first connecting, using FileZilla FTP client, to the built-in FTP server in the NAS I am prompted for accepting DLink's certificate. Once I do that, I am connected. The question I have is that I need to obtain this certificate so that I can use it in an iPhone app so that I can hopefully do the same thing with my iPhone.

Is there any way to either extract the certificate from FileZilla or to pry it out of the NAS?

(sorry if my question announces my lack of understanding, but I am trying to learn)

Thanks in advance for any guidance.