I'm trying to use cifs://server/share to access a folder and it works fine,
but only if server/client are on same subnet. If they are not on same subnet
I get a -36 error. I tried several variations of full dns name, ip address,
etc. but still no luck.

Windows machine access the shares just fine. Is there some other port
involved that needs to be open?
prefer not to use AFP because of simple/universal password stuff.

Is this supposed to work? If not, why does it work whan machines are on same