Aggelos,
This can be caused by a number of factors, especially if there is a firewall involved.
Being that this is a remote verification server, it would require access to the volumes on the Filer in order to perform verification on the LUN's following the SMSQL backup.
First couple things I'd check would involve -
If this continues to be an issue in a production or going-prod environment, I would advise opening a case with NetApp support 888-4NETAPP ( 888-463-8277)
Thanks and hopefully this can get resolved soon!
Christopher