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Tyriado
Tyriado
New Member
July 14, 2021
Question

Strange DHCP conflict

  • July 14, 2021
  • 1 reply
  • 3692 views

Hi. I have a strange problem.

 

I have a network printer. In this printer I set up a manual IP adress and everything works very well. But I have a IP conflict which is little strange.

 

When I go to: Fortiview -> Seources and try to search about that IP I see another (android device) with this IP assigned (?).

 

So I go to Network->Interfaces-> DHCP server -> Advanced and do two steps:

1. Add MAC reservation for my printer MAC and assign them these same IP as printer,

2. Add MAC block for that android device.

 

But I dont knwo ho to force "unassvcigned" that android device from that adress. I try execute dhcp lease-clear 192.168.100.5, but these don't work (I think). I aso try to End sessions in that IP in Soirces, but also don't work. I don't see then that IP in Sources, but after while I see these same android device. 

 

In "User and device"-> Device Inventory I see for that IP adress two devices -  my printer which is offline and that android device which is online.

 

How to fix that rhings ? How can I force to release that IP fro that android device? Is it possible to force that connection somehow? 

    1 reply

    lobstercreed
    lobstercreed
    New Member
    July 18, 2021

    You can't force a device to give up its DHCP lease.  Depending on your lease length, etc, the host is going to think it's valid for the original length of time.  If you can get the Android device to reboot or something you might be able to free that IP up sooner, but if the device is misbehaving (acting as if it has a static IP for example) then your only alternative might be to block the MAC address completely using local-in policy or device security on the interface.

    RPLittledevilcomputers
    RPLittledevilcomputers
    New Member
    July 18, 2021

    If you are going to assign static IP's to your printers you should set them outside of your DHCP range then you will not get an IP conflict. 

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