Windows 10: How to detect LAN item; not recognised by DHCP Solved

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  1.    05 Dec 2017 #1

    How to detect LAN item; not recognised by DHCP

    I have a LAN device that I want to connect to my computer. (It is an interface between my model railway and my computer which has the software to operate it).

    I plug in the Ethernet cable and the port on the device lights up, the hub to which it is attached also lights up and for a few seconds the amber light on the port flashes. Then things settle down and the amber (polling?) light blips every few seconds. I am not that experienced in these matters but that all seems sensible to me.

    However, I cannot 'see' the device on the network. I have logged on to my router and found the DHCP table and nothing changes when I plug/unplug the Ethernet cable from the device. Nor can I access the factory set IP address of the device. I have tried DOS and the 'arp' command but nowhere can I see the device.

    Am I not doing something that I should? I would welcome any insight as to why I cannot see the device given its apparent recognition.
      My ComputerSystem Spec

  2. Caledon Ken's Avatar
    Posts : 10,660
    Windows 10 Pro x64 Build 1803
       05 Dec 2017 #2


    Might be helpful for everyone if you stated make and model of device you are trying to connect for this railway.

    Next could you better describe LAN. You have a modem and router or a modem/router. Your PC connects to....

    The railway connect to a hub and that hub (I think you mean Switch) is then connected to router?

    Has anything changed in environment, like new router or a router reset. Have you check you laptop network, is it set to Private or Public?

    Was Windows recently updated or maybe a better questions, when did this last work?

    Have you tried disabling PC firewall(s) and pinging IP address of device? cmd prompt Ping (using your address range?

      My ComputerSystem Spec

  3.    05 Dec 2017 #3

    In order to initially set up the device, you might have to set your computer to a static IP address that is in the same subnet as the factory IP address of the device. For example, if the factory IP address of the device is, you would set your computer for for example. 192.168.0.xx would be in the same subnet. Then using only the hub not connected to anything else, connect only the computer and the device to the hub. No other connections. Then see if you can ping and communicate with the device via it's factory set IP address.
      My ComputerSystem Spec

  4.    06 Dec 2017 #4

    Hi Ken

    Details: the device is a Lenz 23151 connector that sits between a W10 computer and a Lenz Digital plus system via ‘expressnet’. The LAN has a modem/router (Speedport Entry 2i from Cosmote, my ISP in Greece). I then have 4 Apple airport express WiFi stations (1 base and 3 extenders) to cover a two-story house and a basement (where my model railway is situated). The Airport Express in the basement goes to a hub/switch and then to a W10 computer that runs the software for the train control and also to the 23151 device which is also connected to the Lenz computer system.

    Nothing has changed lately in this setup and I cannot ping the device (no response, timed out).


    I followed your suggestions and then I could ping my device OK. However, when re-setting the (local) computer back to its ‘use DHCP’, I was again unable to communicate. The factory set IP address of the device is and all my other network items have addresses I am guessing that this may be the root of the connection problem and, if so, I am looking either to change the IP address of my device to or to do something to change way the DHCP allocation of addresses in my router/modem works.

    I also tried setting my computer to in the hope of moving forwards but this messed up my internet access and W10 sorted this out by setting me back to DHCP again.

    I may be off on a wrong idea here but I would appreciate a way to tidy up this problem.
      My ComputerSystem Spec

  5. Barman58's Avatar
    Posts : 2,788
    Windows 10 Pro x64 1803 - 17134.5 XP/Vista/Win7/Win8.1 in VM for testing
       06 Dec 2017 #5

    The basic issue here is you have two SubNets, I think - we'll call them 192.168.0.x and 192.168.1.x, which by the nature of networking will not communicate with each other. this explanation can only be used as a guide as we are missing Vital information in regards to actual IP addresses used

    You have two possible ways to get this sorted out, you either need to add a router into the system to "translate" between the two subnets,

    or you can combine the two subnets into one, (This is the best option IMHO).

    Decide which of the subnets are easier to re-assign, I would suggest that the Internet connected subnet is the easiest, as I do not know the workings of the Lenz 23151

    You will need the manual for your router, and any airport devices (if these are set-up manually).

    You need to reset your router IP to an address in the same range as the Windows 10 Railway controller PC connected to the Lenz 23151 we'll call this RCPC

    Check the IP address of this RCPC and you then need to set the router IP address to an address in the same range, suggest 192.168.n.1 where n is the number in the RCPC and also set the router DHCP to the same range

    EG if the RCPC has a preset of the Router would need to be set to (I suggest to prevent clashes), and the DHCP range to to This will leave you a number of addresses that can if needed be set manually as the system changes/grows any (IP address from to

    These are just suggestions / examples as I do not know the amount of customisation possible with the components of your system if the Lenz 23151 has to have the controlling PC in a certain subnet range or even a specific IP address then this is the controlling factor in how you set up your other components.

    If you need more specific assistance I would need more specific data such as the IP settings of the RCPC and the router

    In the spirit of learning there is an explanation of IP and Subnetting here
    (I apologise for the title which follows the book series) this is only for completeness and I'm sure that If you can give us specifics of your system currently the rest will be easy to do
    Last edited by Barman58; 06 Dec 2017 at 04:40.
      My ComputerSystem Spec

  6.    06 Dec 2017 #6

    Many thanks for this! I can see what you are saying and need to get to work with the Router manual, etc. and see if I can do it!

    I will let you know how I get on.

      My ComputerSystem Spec

  7.    06 Dec 2017 #7

    Most devices you can change the IP they use to what ever you want. The other option is to use the route Cmd in Windows to set a route to the device
      My ComputerSystem Spec

  8. Caledon Ken's Avatar
    Posts : 10,660
    Windows 10 Pro x64 Build 1803
       06 Dec 2017 #8

    Hi Alan you are on the right track but something changed as these are now two different subnets.

    The route of changing your router IP range is likely the easiest, one they even talk about in manual.

    The process to change your Lenz device is also outlined in manual. Starting on page 5.

      My ComputerSystem Spec

  9.    06 Dec 2017 #9

    I am descending into unknown areas and while I can see the implication of two different subnets, I am concerned about doing something unintended that will lock me out from the internet!

    The DHCP table in my router looks like this with apologies for the formatting:

    DHCP server On

    LAN IP address 192.168. 1. 1

    Sub-net mask 255.255.255. 0

    DHCP start address 192.168. 1. 2

    DHCP end address 192.168. 1.254

    It then goes on to indicate that the ISP DNS is off.

    A simple question is whether I can change the DNS server table to something like

    DHCP server On

    LAN IP address 192.168. 0. 1

    Sub-net mask 255.255.255. 0

    DHCP start address 192.168. 0. 2

    DHCP end address 192.168. 1.150

    Is this what you are suggesting, Barman58? This would seem to leave my device ( clear of the DNS allocated addresses but would this leave the system running OK and allocate to all my other networked items? Or have I missed something important?

    Thank you, all.

      My ComputerSystem Spec

  10. Barman58's Avatar
    Posts : 2,788
    Windows 10 Pro x64 1803 - 17134.5 XP/Vista/Win7/Win8.1 in VM for testing
       06 Dec 2017 #10

    Alan, that should work without any issues,
    I suggested that you reduce the DHCP range as I was not certain of the way that the Apple devices were set up, if they are currently set manually you should use addresses outside the DHCP range if not then leave them as is - it's actually quite normal to manually assign IP addresses for "Network Infrastructure devices" such as extenders and sub routers as these are better found if the IP is fixed.

    If the extenders are manually set for IP, (back to the Airport Router), then you need to bear this in mind and allocate IPs from the non DHCP range

    I personally tend to use pre allocated DHCP IP addressing, which forces the IP through DHCP, rather that manual method, as this gives me better centralised control, (single change of the router settings changes everything without having to change individual items) - but I digress manual allocation is simple enough to do in a home network rather than the systems I have worked with where you can have hundreds or thousands of devices
      My ComputerSystem Spec

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