DHCP IP Duplication on wired and wireless - R7800 - Nighthawk X4S

[Zonker]

Just purchased and set up my new R7800 tonight.  As I was going throught the attached devices list, I noticed I had two different devices with the same IP address.  The difference being that one was a Wired device (NAS device) and the other was a wireless device (Thermostat).  Strange thing is I can access and control these device through the LAN (for the NAS) and through a wireless app (thermostat).  How can this even be possible?  How is it the same IP address with different MAC address can even respond without a conflict?  There is no warning on the Thermostat or on the admin page of the NAS.

Thanks,

Z 

[TheEther · Accepted solution]

You should never allocate a static IP address within the range of addresses managed by a DHCP server.  As far as the DHCP server is concerned, it has sole control over delegating those addresses.  Any static IP addresses you allocate must be outside the control of the DHCP server.

You should change the NAS's IP address or else change the DHCP range to avoid the conflict.  For example, suppose your NAS is using 192.168.1.2, then set the DHCP range to 192.168.1.3 through 192.168.1.100.

[Retired_Member]

One of them may have a static IP setup check nas first

[Zonker]

Yes this is correct, my NAS has a static IP address.  So why would the DHCP server allocate the same IP address for the thermostat?  Anyway I flushed the thermostat IP and it now has a unique IP. 

Z

[TheEther · Accepted solution]

You should never allocate a static IP address within the range of addresses managed by a DHCP server.  As far as the DHCP server is concerned, it has sole control over delegating those addresses.  Any static IP addresses you allocate must be outside the control of the DHCP server.

You should change the NAS's IP address or else change the DHCP range to avoid the conflict.  For example, suppose your NAS is using 192.168.1.2, then set the DHCP range to 192.168.1.3 through 192.168.1.100.

[Retired_Member]

When using static IP's you have to use IP's that are not in the DHCP range. The DHCP didn't allocate it You did when setting a static,the DHCP has no idea what IP is assigned by you because it didn't assign it.

Use address reservations

[Zonker]

How can you assign static IPs outside of the DHCP range?  Reservations require the IP address to be within the range you specify.

Thanks,

Z 

[Retired_Member]

Static and address reservations ARE NOT the same thing. That's how! Many people assume they are which is wrong.

DHCP address reservations assign same IP to any device set to DHCP