Printer ports shared with NET USE disconnect after few minutes


Juan Carlos


I have a old DOS program that was working fine in Windows XP. This program
uses LPT1, LPT2 and LPT3 ports to print tickets and more.

Now we have bought new computers with Vista installed and we have a lot of
problems. I want to explain one of them.

I have configured the printers and using NET USE LPT2: \\computer\printer
/PERSISTENT:yes because I use printserver for the stand-alone printers.
it can print on all the ports with no problem. I had done a lot of test and
the printers work fine, but when the computer stay few minutes not working
when I tried to send a job to the LPT2 or LPT3, the ports was disconnected.


LPT2 -> Disconnected
LPT3 -> Disconnected

After that, I send some data to that port, for example, ECHO Test > LPT2 and
first time appears a message with a port not ready alert, and second time it
prints fine. Now, when I test NET USE again appears:

LPT2 -> Connected

I do not understand this problem, but I think can be a new system
configuration from Vista, because everything were working in XP with the
same configuration for a long time.

Sorry for my poor english,

Best regards,

Juan Carlos



Robert L. \(MS-MVP\)

This is an interesting issue. When XP and windows 2003 came, many people
have an auto disconnection issue. I would like to find it out if it is
similar thing. Does the computer connecting to the printer is server or

Networking, Internet, Routing, VPN Troubleshooting on
How to Setup Windows, Network, VPN & Remote Access on



Juan Carlos

Printers are conected to an ethernet printserver.

Printserver has 3 ports, lp1, lp2 and lp3.

I install a printer.
Add a new TCPIP port that connect to the printserver and its port.
Then I print a test to be sure it is working fine.
I share the printer to the network.
Finally, use a batch file with NET USE port: \\computer\printer
/persistent:yes commands.

First time, I send some data to the printer and it can be printed. When I
see NET USE, appears the LPTn port connected. Few minutes after, it is
disconnected when there are no jobs.

I had configured it in XP and no problems. Vista, new S.O. new problems.

Thank you very much

Juan Carlos

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