Windows has detected an IP address conflict Networking Origin: Network OSI layer 2 · Data Link Last updated 5 Nov 2026

Networking: Windows has detected an IP address conflict / Duplicate address detected by 00:aa:bb:cc:dd:ee

Two devices on the same network are using the same IP address, so traffic reaches the wrong one or neither.

Exact message you may see Windows has detected an IP address conflictThere is an IP address conflict with another system on the networkDuplicate address detectedarp: duplicate IP address 192.168.1.50IP address conflict
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Seen on: Windows Linux Networking

Meaning

Find the second owner with arp -a (or arping -D) and compare MAC addresses. Fix it by moving the static address outside the DHCP pool, creating a DHCP reservation, or renewing the lease; a laptop waking with an old lease and a printer with a manual IP are classic causes.

Common causes

  • Static IP inside the DHCP pool
  • Two devices configured with the same manual IP
  • Stale lease on a device that woke up
  • Second DHCP server handing out the same range
  • VM clone with the same IP

⚡ Quick fix

  1. Identify both MACs: arp -a / arping -D -I eth0 192.168.1.50
  2. Move statics out of the pool or add a DHCP reservation
  3. Renew the lease: ipconfig /release and /renew

Detailed fix by platform

Windows

  1. powershell
    arp -a | findstr 192.168.1.50
ipconfig /release && ipconfig /renew

How to diagnose

  1. MAC addresses — Two for one IP?
  2. Static IP — Inside DHCP pool?
  3. DHCP — Single server?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

Where this error sits

Origin: Network. Errors that are often confused with or caused by this one (click to open):

169.254.x.x self-assigned IP (DHCP failed) — Networking: IPv4 address 169.254.x.x (Autoconfiguration / APIPA) — the PC couldn't get an address from DHCP (Networking)169.254.x.x self-assi…arp -a shows (incomplete) — Networking: `arp -n` shows (incomplete) / Destination Host Unreachable — no ARP reply from the next hop (Networking)arp -a shows (incompl…DHCPDISCOVER ... No DHCPOFFERS received — Networking: dhclient: DHCPDISCOVER on eth0 ... No DHCPOFFERS received. No working leases in persistent database - sleeping. (Networking)DHCPDISCOVER ... No D…DHCPDISCOVER: no free leases — Networking: dhcpd: DHCPDISCOVER from aa:bb:cc:dd:ee:ff via eth0: network 192.168.1.0/24: no free leases (Networking)DHCPDISCOVER: no free…Network cable unplugged / NO-CARRIER — Networking: Network cable unplugged / `ip link` shows NO-CARRIER state DOWN / Ethernet: Network cable unplugged (Networking)Network cable unplugg…Rogue DHCP server hands out wrong gateway/DNS — Networking: Clients receive the wrong default gateway or DNS server — a rogue DHCP server (often a home router) answers first (Networking)Rogue DHCP server han…Windows: Default gateway is not available — Networking: Windows: Default gateway is not available / Diagnose Connection Problems: DHCP not enabled (Networking)Windows: Default gate…Wrong subnet mask: hosts can't reach each other — Networking: Two hosts on one LAN can't talk — subnet mask or network address mismatch (Networking)Wrong subnet mask: ho…Windows h…

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