When you use NET USE or NET VIEW across a Dial-On-Demand router or slow link and the connection attempt is longer than 45 seconds, a "Semaphore Timeout" error message appears. By default, the Windows NT redirector time-out value is 45 seconds, which limits the length of time a connection is made. To change the redirector time-out value:

Hive: HKEY_LOCAL_MACHINE
Key: SYSTEM\CurrentControlSet\Services\Rdr\Parameters
Name: ConnectMaxTimeout
Type: REG_DWORD
Value: Number of seconds

Documented default is wrong: Q148127 - DocErr: ConnectTimeout and Default Time-out Are Incorrect,