Totally new on networking and on switches, so excuse me if I use some wrong terminology.


I have 1 computer and 7 instruments. I would like to form a network setup fulfilling the following requirements:

  1. A LAN for computer+instruments.
  2. The computer needs to be connected to an outside WAN.
  3. The instruments should not be directly addressable.
  4. I wanna set this up and not tweak anything for long periods of time. The instruments can be set to have static IPs.


There is an already installed HP1820 (24 port) switch on the instrumentation rack I am using. 4 ports of it occupied with instruments using reserved WAN IP addresses (let's call it 192.168.1.x). My question is:

  1. Can I use this device to form a LAN with the e.g. IP space 10.10.0.x for computer+instruments?
  2. Can this configuration also accommodate the computer having a reserved WAN IP (supplied by my institution)?

Below is a mock up graphic for what I'm trying to say: example

If this is not possible I am going to opt for buying a router with 8 LAN ports and 1 WAN port and connect to the switch. Is there any better option than this?

I am not in charge of the switch, and currently don't have an access to it. If it's possible I may ask the person in charge to use it, so that's basically why I can't try it out.

1 Answer 1


You cannot simply use a switch to connect different IP networks. The switch can form a LAN but it cannot connect that to "WAN". You need a router between and "" WAN/uplink.

If the upstream router doesn't know about then the router needs to use source NAT. If you need access to the network from "WAN" then you need to use destination NAT aka port forwarding as well.

If you just want connectivity from the PC to both networks you can use two NICs in the PC and partition the 1820 ports into two VLANs (or simply use one NIC for "WAN" and one for the 1820 LAN). Instead of two NICs you could use VLAN trunking between switch and PC if that is supported.

  • Thank you very much for your answer! Yes, I only need the computer to have access to the WAN, I may install VPN software to that computer if I need later. Is this "VLAN trunking" an extra feature that my specific switch may have? Mar 19, 2019 at 6:36
  • 1
    The 1820 series supports VLAN trunking (just configure multiple VLANs and set them as tagged or untagged on ports as required), but the PC NIC needs to be able to use 802.1Q VLAN tagging as well. This depends on the hardware, its driver and the OS (off-topic here on NE).
    – Zac67
    Mar 19, 2019 at 8:04

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