external printserver

Hallo,

I have a substantial and ongoing problem with external printservers.

Start of the whole problem is some weeks ago. Suddenly the first and then
the second printserver ( DLINK DP300+ ) made mistakes in that way, that he
lost contact to the network and had to be switched off and on to get contact
again. This problem was well known and solved in the past with the change of
the printserver. The DLINK-Printserver were substituted by INTEL Printserver
NETPORT 10/100. Problem was not solved. The Printserver lost contact
sporadic 0-2 times a day.
Once again we thought the problem were the printserver, because one other
printserver worked very well. We changed to HP Printserver 170x ( 10 MBIT ).
Problem remained the same.
Next ist that we changed the switch to LINKSYS and set the ports for the
printserver hard to 10 MBIT. Nothing changed.
By the way the third printserver worked on very well and not one of the 20
workstations lost one time contact to the network.
Next was that a new printer / copier from UTAX with an internal network card
was installed. This machine showed the same symptons as the two failing
printservers and lost contact from time to time. What we found out was, that
if one has time enough after appr. 1/2 hour the print suddenly was executed.

The network is based on a windows 2000 Server SP4 and two Terminal Servers
Windows 2003 R2 SP1.

I tried two ways of connecting the printers to the network: installed on the
server and shared to the terminal servers as well as installed on the
terminal servers directly. All the time the same result.

All three printservers are running in the same segment over the the switch.
Connecting the failing printservers as well the the UTAX Machine directly to
a notebook lead to no mistakes.

What else I can do or what could the mistake be? Has anyone an idea?

Thanks in advance

Jürgen Dankow

Sorry for my english. Hope you can understand my problem.