vmware alternate restore hang on certain media server

Hello

I am experiencing a little strange thing when using a certain media server as recovery host the restore creates the virtual machine, sets the snapshot and establish the nbd connection to the esx host and then nothing happens

Netbackup 7.5.0.6 (Yes know that I should upgrade to 7.6.0.X ) on Windows 2008 R2

Wondered if anybody had seen something like it before ?

I already have a case at Symantec

Regards

Michael