#1529 Connection delayed with an optic fiber network connection

[Vigier Guitars]

Hello,
On the same machine.
Windows 7 client and server.
If my server machine is connected on a classic ADSL network connection, the connection is immediate.
If the machine is connected by an optic fiber network connection, the connection is either long or time out... once done the connection is fast and reliable.
Any idea?
Thank you
Patrice