Hi! Please sign in Home >  Support > Technical FAQs

Technical FAQs
Question I can PING & Telnet NPort, but why can not NPort connect with my own TCP Server program properly?
Question Type Application
Updated 4/1/2008 3:44:37 PM
Hits 19800
Products NPort 5230 Series,NPort Express DE-211,NPort Express DE-311,NPort 5210/NPort 5230/NPort 5232 Series,NPort 5410/NPort 5430/NPort 5450 Series,NPort 5430 Series,NPort 5610/NPort 5630 Series,NE-4100T,NE-4110S,NE-4110A,NE-4120S,NE-4120A,NPort Server Lite DE-301/302/304/331/332/334



1. Improper operation mode.

2. NPort's connecting TCP port is not correct.

3. DHCP issue.

4. Improper [Desti. IP] setting.

5. NPort is connected to another TCP Server.

6. Firewall filtering rules.

7. Improper DIP switch settings on DE-311/211.


  • Your operation mode must be [TCP Client mode].
  • The NPort's TCP Port must match your own TCP Server program.
  • If your Host and NPort are in a DHCP environment :
    a) You have to assign a fixed IP address to NPort & your Host.
    b) Under a DHCP environment, you can map a specific IP address to your NPort's & Host's MAC address.
  • Your [Desti.IP] must be the same as your host’s current IP.
  • Telnet NPort's IP address, and check the ''Conn. Status'' message under [Monitor]. It must shows ''Remote x.x.x.x'' (x.x.x.x must be your host's IP).
  • Make sure that your firewall can open the TCP port.
  • The DE-311/211's DIP SW1 must be OFF for data communication.

Related Questions
Provide Feedback
Quality of this article
Poor                Excellent