Two devices on the same network can't share the same IP — when they try, both get knocked offline and you see an "IP address conflict" warning. Here's how to find the conflicting devices and stop it from recurring.

Why conflicts happen

• Someone manually set a static IP that overlaps with the DHCP pool
• An old device's lease expired but DHCP reassigned the IP before the device fully released
• Two routers with overlapping DHCP scopes on the same subnet
• A static device woke up and grabbed an IP DHCP had already handed out

Step 1: Release and renew

The fast fix: force the device to ask for a new IP. Run release and renew. Often resolves immediately.

Step 2: Identify the conflicting devices

1. Log into your router admin page.
2. Open the DHCP Clients or Attached Devices list.
3. Find duplicates — same IP listed for two different MACs or hostnames.

From command line: arp -a (Win/Mac/Linux) lists every IP+MAC pair your machine has talked to recently. Duplicates here = conflict.

Step 3: Permanent fix — DHCP reservations

Instead of static IPs configured on each device, use DHCP reservations in the router. You assign "this MAC always gets this IP," but DHCP still hands them out — so there's no chance of conflict. Configure under DHCP → Reserved Addresses.

Step 4: Resize the DHCP pool

If your router gives out 192.168.1.100–199 (100 addresses) and you have 80 devices, you're crowded. Expand the pool to 192.168.1.20–250 to leave room for static IPs at the low end. Set static IPs outside the DHCP range.

Step 5: Catch repeat offenders

If conflicts keep happening despite fixes, one device is probably stuck with a static IP someone forgot about. Network printers, IP cameras, NAS boxes, and old smart-home hubs are the usual suspects. Check each one's network settings for hardcoded IPs.

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