What you’re seeing
- Some computers get addresses like 192.168.0.x or 192.168.1.x when the office normally uses a different range.
- Affected devices have internet but cannot reach the file server, printers or domain, or the other way around.
- Problems appear randomly on different machines depending on which device answers first.
- The issue began after someone plugged in a home router, a Wi-Fi extender or new equipment.
- Users see 'Unidentified network' or cannot sign in to the domain from some desks.
Common causes
Every environment is different, but these are the causes our engineers find most often:
- A consumer Wi-Fi router was plugged into the office network by a LAN port, and its built-in DHCP server is active.
- A new firewall, ISP gateway or access point came with DHCP enabled by default.
- A virtual machine, test lab or network-attached device is running its own DHCP service.
- Two legitimate DHCP servers, such as a router and a Windows server, are both handing out addresses.
- A malicious device on the network is offering addresses to redirect traffic, which is a known attack technique.
Why it matters
DHCP tells every device where to find the internet, DNS and your servers. A rogue source sends some machines down the wrong path, so they lose access to shared files, printers or the internet at random. Because only some machines are affected and it changes over time, staff waste hours on confusing symptoms. A rogue DHCP server can also be used deliberately to intercept traffic, so the source should be identified quickly rather than left running.
How AskTechGurus fixes it
Skip the trial and error. A certified engineer works on your actual system, finds the root cause, and fixes it properly.
Tell us what’s happening
Submit a ticket in about two minutes. Paste the error, describe what changed, and pick your tier. No charge to submit.
A certified engineer diagnoses it
A vetted, US-based systems engineer claims your ticket, usually within minutes during business hours, and investigates over a secure remote session you can watch and end at any time.
Fixed and verified with you
The engineer resolves the root cause and confirms with you that it’s working. You don’t just get a workaround, and you get a plain-English summary of what was wrong.
Pay only when it’s resolved
Fixed price from $99, invoiced only after you approve the fix. If it isn’t resolved, you don’t pay.
Frequently asked questions
How do we know if it is just an extra router or an attack?
Most cases are an innocent consumer router or new device with default settings. Identifying the physical device behind the rogue address answers the question, and anything unexplained should be treated as a security concern.
Why are only some computers affected?
Devices take whichever DHCP answer arrives first, so the outcome depends on timing and where each device sits on the network. That is why the symptoms look random.
Can you track it down remotely?
Often yes, with access to a PC and your network equipment. A certified US engineer hunts it down through a remote secure session, from $99, and you pay only when every device is getting the right address.