Can do using LAN IP addr
Nothing in the firewall blocking imap - I think it is in the server config.
As I was using SSH to access the server previously, I decided to go in to the client and try imapsync directly on the server - same timeout result!
Tried the quick imap telnet check to server.net 143 and that was a no go.
Decided to use server's IP since I was at the site and ...voila - she speaks.
So re-ran the imapsync from another station using SSH and the server's IP and off it went.
Anyway, since the email migration is the priority now, I am proceeding with that. I still need to check on the server's config to see what's up with the imap 143 blocking for future reference if I have to do this on another server.
Thanks for those who took the time to check in on this, and also Falko for your input.