Member Avatar for hosp_IT_ality

Hello All. I apologize in advance if there is already a thread out there describing this issue but I was unable to find it or unable to describe it efficiently within a quick phrase. I'm stumped on the following issue and would appreciate any help.

At the Resort where I work as a Network Administrator I have two networks that are entirely separate from one another.
One is a guest wireless network Class A
and one is an internal Class C which serves our Domain group.
When a guest attaches to our wireless (Class A) they receive a 10.71.0.x IP address, validate via our redirect splash page and can then surf. Pretty standard for public Wi-fi in a hotel setting.
Well, a few of my co-workers that also have access to the wireless, have one model of Laptop (Dell Latitude D810) that "occasionally" connects to the wireless network but grab a Class C IP address but it's a Phantom. Usually 192.168.1.x. Now what's really wierd is that the laptop sees the right Default Gateway and DNS and can also be set to statically connect to the wireless but won't get the correct IP. DHCP is handled by each Access Point so dishing out a 192.168.1.anything is not possible. I've set up each AP personally so I KNOW without a doubt that the issue isn't with the AP's.
I've tried all the usual suspects, removed drivers, checked LMHOSTS, HOSTS, TCP/IP, profile setups and the like but still the same result. It's almost like the laptop is serving as it's own DHCP but darned if I know how. Everyone here is thoroughly stumped. Any help or points in the right direction would be appreciated. Sorry for the length of this but it's a tough one to summarize.

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Dani AI

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Solid troubleshooting so far, and . When an unexpected private address consistently “sticks” to one endpoint rather than to the infrastructure, the cause is almost always client-side: a local alternate IPv4 configuration, a virtual/TAP adapter, a soft‑AP/ICS service, a persistent route, or a driver/hosted‑network artifact. The checks below are targeted and non‑destructive, intended to reveal which of those is in play.

Collect the following diagnostics (adapter names and the DHCP server shown in the output are the key clues):

ipconfig /all
netsh interface ipv4 show config
netsh wlan show hostednetwork
route print
sc query SharedAccess
netsh wlan show profiles

Interpreting results: ipconfig /all identifies which interface actually owns the problematic address and which DHCP server issued it; netsh interface ipv4 show config exposes any Alternate Configuration entries; netsh wlan show hostednetwork reveals a Microsoft virtual AP; sc query SharedAccess shows whether Internet Connection Sharing is active; route print shows persistent routes that can redirect traffic through the “wrong” interface. Virtual adapters (VMware, VirtualBox, VPN TAP, Hamachi) often introduce private ranges; Device Manager will list them.

Remediation notes tied to the likely causes: remove any unwanted Alternate Configuration in the adapter’s IPv4 properties; disable or uninstall unneeded virtual adapters or VPN TAPs; stop and disable any hosted/softAP or ICS services; remove persistent routes if present. If the adapter/driver is suspected after configuration checks, test with an alternate radio (USB/PCMCIA) or disable the onboard wireless in firmware to isolate hardware. As a last step for stubborn configuration residue, reset the networking stack (for example: netsh winsock reset and netsh int ip reset) after exporting saved wireless profiles.

These steps build on ’s isolation suggestion and complement the registry inspection mentioned earlier by focusing on the common client‑side causes that travel with a single laptop rather than the APs.

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Member Avatar for Freaktech

Are you absolutely positive that you don't have a rogue AP somewhere in the building? Do they pull the 192.168.1.x addy in the same area of the hotel everytime? If so that definately points to a rogue AP.

Member Avatar for hosp_IT_ality

Thank you Freaktech for your response. I really appreciate your input and your time.

No doubts about a rogue AP. The hotel is quite expansive (covers 2000+ acres including condos and townhomes in outlying areas) Conveniently enough the laptop belongs to our Associate Housing Director who moves freely all about the Resort. This issue happens everywhere including the local Panera Bread. Always a good Default Gateway and DNS but always with the or 46 IP.
I designed the wireless and have really good monitoring software in place and I know every AP intimately including each AP's footprint. One may say I'm obsessive about my network. I'm quite sure it's not a rogue AP and have confirmed that the laptop gets stuck on the same IP even within the footprint of different APs. Also, we have hundreds of guests daily that use the wireless and no other person has reported such an issue.
NEW INFO: I discovered that the user of the Laptop uses high-speed wireless at home that uses a 192.168.0.x address range. Ah-Ha! So now I know "where" they got the IP just not why it won't drop it despite being set to DHCP. I'm left scratchin' my noggin'.
Any thoughts?

Member Avatar for Freaktech

Thank you Freaktech for your response. I really appreciate your input and your time.

No doubts about a rogue AP. The hotel is quite expansive (covers 2000+ acres including condos and townhomes in outlying areas) Conveniently enough the laptop belongs to our Associate Housing Director who moves freely all about the Resort. This issue happens everywhere including the local Panera Bread. Always a good Default Gateway and DNS but always with the or 46 IP.
I designed the wireless and have really good monitoring software in place and I know every AP intimately including each AP's footprint. One may say I'm obsessive about my network. I'm quite sure it's not a rogue AP and have confirmed that the laptop gets stuck on the same IP even within the footprint of different APs. Also, we have hundreds of guests daily that use the wireless and no other person has reported such an issue.
NEW INFO: I discovered that the user of the Laptop uses high-speed wireless at home that uses a 192.168.0.x address range. Ah-Ha! So now I know "where" they got the IP just not why it won't drop it despite being set to DHCP. I'm left scratchin' my noggin'.
Any thoughts?

Sounds like a bad wireless card. Either a bad driver or actual hardware. Oh I am the same way with my network. Nothing goes on that I don't know about. It kinda scares my bosses. I had one bring in his son and let him connect to his personal laptop to my wireless. Not 5 minutes later I was informing him that he could not do that per the Network usage terms he signed, which I wrote.

Member Avatar for hosp_IT_ality

That's awesome! It's like I say, "Don't hire me if you don't want me to my job." Disobedience will not be tolerated! I suspect we're birds of a feather.
So anyway, I'm inclined to agree about the wireless card. weird though. I want to check the registry values under "Netbt\Parameters\Interfaces\Tcpip_ID for Adapter" before I hurl the towel into the ring and overhaul the mobo but I suspect it'll be yet another wall. Just gotta know though. I'll close this thread once I know all that. Thanks again, Freaktech.

Member Avatar for Freaktech

You wouldn't have a USB dongle or a PCMIA card you could try? I would disable the onboard and try that first.

Member Avatar for hosp_IT_ality

Kinda been there...
I attached a Linksys Desktop wireless bridge and had no issue. The bridge grabbed the signal, sent it to the NIC and Grabbed a IP address just like a good li'l girl. The laptop just thought it was plugged into an ethernet port. No issue. But I did not try PCMCIA or USB. What can it hurt though. I'll try it tomorrow. Thanks FT.

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