IPV4 Static Address reverts to "Obtain an IP address automatically"

  1. smartcooky's Avatar
    Posts : 154
    Windows 10 Home 32 bit
       #1

    IPV4 Static Address reverts to "Obtain an IP address automatically"


    Win 10 Pro, 64bit
    Ver 21H1



    We have a network that has five computers, an Ethernet attached printer, an EFTPOS terminal and a Wifi enabled SD card connected. Each device has a fixed IP and we use a hosts file in windows C:\Windows\System32\drivers\etc
    This might seem an odd way to do it, but it is a necessary one because of the way the EFTPOS and Wifi SD card operate - they both have fixed IP numbers that we cannot change. I will explain about this at the end if anyone is interested.
    The problem we are having is that one of the computers reverts to "Obtain an IP address automatically" on every reboot. This is the procedure I follow, which I hope is correct...

    Control Panel > Network and Sharing Centre > Change Adaptor Settings
    Right-click on the Adaptor and choose Properties
    Left-click on Internet Protocol Version 4 (TCP/IPV4)
    Click the Use the following IP address radio button and input
    IP Address 192.168.1.99
    Subnet Mask 255.255.255.0
    Default Gateway 192.168.1.1
    Check the box marked Validate setting upon exit
    Click OK and Close
    Check to see if it has worked by going to any other computer on the network and using an Admin Command Prompt to run the command arp -a which lists all the IP numbers in use on the network. "99" is there!
    Then I reboot the computer computer in question, and check arp -a again, and "99" has gone,replaced with some other number. When I check the TCP/IPV4 settings, it has reverted to "Obtain an IP address automatically". I cannot get the static IP number to "stick". Is there anything I am doing wrong here - am I missing some obvious or non-obvious vital step?

    ******
    Why our network is configured the way it is.
    The Wifi card is in our shop camera, and it only comes on line when some photos have been taken and the card wants to send them. It connects to 192.168.1.65 by default. After a few minutes, the camera turns off and the card disconnects. Similarly, the EFTPOS terminal (192.168.1.20) only connects to the network when its Logging On, putting through a transaction or running the EFTPOS Settlement at the end of the day.
    If we allow our computers to "Obtain an IP address automatically", sooner or later, one of them will steal the Wifi Card or EFTPOS terminal fixed IP, and that device won't work.
    Last edited by smartcooky; 4 Weeks Ago at 06:43.
      My Computers

  2. Samuria's Avatar
    Posts : 6,453
    windows 10
       #2

    You can do it the other way most routers even running dhcp on the router you can tell it to always give a pc a certain ip. When you set ip from cmd prompt type
    Ipconfig /all

    Post results reboot and run again post results.
    It could be the ip is in use or reserved
      My Computer

  3. smartcooky's Avatar
    Posts : 154
    Windows 10 Home 32 bit
    Thread Starter
       #3

    Samuria said:
    You can do it the other way most routers even running dhcp on the router you can tell it to always give a pc a certain ip. When you set ip from cmd prompt type
    Ipconfig /all

    Post results reboot and run again post results.
    I don't understand this. I have no idea how to make a router assign a specific IP number to a specific computer. That is why I do it with a hosts file and modifying the properties of the Ethernet Adaptor. This has always worked flawlessly for me in the past. Are you suggesting that I entirely change the system for the whole network to work around one computer with a defect?

    Samuria said:
    It could be the ip is in use or reserved
    I don't think so.

    If the number I chose was reserved, then the computer in question would not be able to connect to the network using that number, but it does, It all works perfectly. It can reach all the other computers on the network and vice-versa. It is only after a reboot that the computer resets the adaptor TCP/IPV4 from "Use the following IP address" to "Obtain an IP address automatically" To be clear, even when the adaptor reverts to "Obtain an IP address automatically" the computer still appears on the network and everything works OK, its just that occasionally, it allocates itself 192.168.1.20 or 192.168.1.65, and when it does so, that stops either the EFTPOS terminal or the Wifi SD Card from working.

    Besides, I have tried using several different IP numbers, and it makes no difference... the number appears on the arp -a list, and everything works fine with other numbers.
      My Computers

  4. Bree's Avatar
    Posts : 21,183
    10 Home x64 (21H1) (10 Pro on 2nd pc)
       #4

    smartcooky said:
    .The Wifi card is in our shop camera .... It connects to 192.168.1.65 by default. ..., the EFTPOS terminal (192.168.1.20)...

    ...If we allow our computers to "Obtain an IP address automatically", sooner or later, one of them will steal the Wifi Card or EFTPOS terminal fixed IP, and that device won't work.

    Almost every router I've seen, even the free one I got from my ISP, has the ability to set the range of IP addresses in the pool it allocates from. The simplest solution would be to set your router's DHCP server address range of IP addresses to start at 192.168.1.66. Then no PC can ever get assigned either of those two critical IP addresses. This also means you can forget about assigning static IP addresses to every PC, one setting on your router should fix it for all current and future PCs on your network.

    Here's my router's control panel as an example....

    IPV4 Static Address reverts to "Obtain an IP address automatically"-image.png
      My Computers

  5. smartcooky's Avatar
    Posts : 154
    Windows 10 Home 32 bit
    Thread Starter
       #5

    OK, I will have a look at that on Monday
      My Computers


 

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