Wrong DHCP server

We are running a network on the 10.0.0.x subnet. We have another subnet on the DMZ of our Fortigate Firewall of 10.0.1.x

We have a wireless access point that is on the 10.0.0.x subnet.

We have a Windows 2003 SBS Server that is giving out IP's on the 10.0.0.x subnet.
The Fortigate is giving out IP's on the 10.0.1.x subnet.

We have ONE laptop that keeps getting an IP from the 10.0.1.x subnet but it says it is connected to the above WAP that is on the 10.0.1.x subnet.

If I plug the network cable in, it gets an IP from the server (where it should get an address). If I connected wirelessly, it gets an address from the 10.0.1.x subnet (which doesn't get to the server or have internet access).

I have taken my laptop, Android phone, iPad, etc. in his office and on ALL THREE wireless devices I get an IP address from the 10.0.0.x subnet.

Anyone have any ideas as to how I can fix this?
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Nick RhodeIT DirectorCommented:
Static Address?
CorinTackNetwork EngineerCommented:
Have you checked the server to see if it is, in fact, handing out an IP address to this laptop via the wireless?

If so, it could be that the laptop somehow has a reservation on the server's DHCP. You'll want to check that, as well as deleting the laptop's DHCP lease from the server and trying again via ipconfig /release and /renew, or just by rebooting the laptop afterwards.
DocomonAuthor Commented:
It doesn't have a static IP address. Checked that also.
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DocomonAuthor Commented:
It's not getting an address from the server. That's the one I WANT it to get one from. It is getting an address from the Fortigate DMZ subnet. The Fortigate is giving out addresses on that subnet, however, the WAP that the laptop is connecting to is on the 10.0.0.x subnet (the right subnet). Strange issue!
DHCP is a broadcast based system...so basically the Fortigate is sending its message prior to the SBS server...

How is the WAP connected in this network? Eg you have a Fortigate - is the WAP on the SAME switch as the fortigate? Or have you just 1 switch connecting everything together?

From what is happening its possible the WAP is connected closer to the Fortigate than the SBS...this can happen if the WAP is on the same switch as the Fortigate - it will always in that case get and hand out IP's from it

Also your WAP is a Layer2 device...doesn't matter that is has an IP on the 10.0.0.x network - that IP doesn't determine how traffic passes through it...its simply a management address...

So explain how things are wired up and that might get us closer to the answer here

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DocomonAuthor Commented:
I moved where the WAP was plugged in (to a different switch that the DMZ wasn't plugged into) and the problem went away!

I will monitor this for a few days to make sure the issue is resolved for sure but it appears to be fixed!
Good stuff...glad to assist.
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