when you run the 'custom command' the nsh session is initiated from your client, not the appserver. unless your nsh client is configured to use a nsh proxy ( in which case the connection would go nsh client -> nsh proxy -> target). so can your client connect to 4750 on the target directly ? my guess is no.
Oh yes..u r right. I recently changed our console server after the upgrade and i forgot about this.
Thanks Bill for your quick help.