Repair duplicate IP address on network issue.
- Turn off everything on the network, ALL the machines and any other network device like network printers and NAS drives.
- Turn off the router and modem.
- Turn on the modem, wait for a steady data light.
- Turn on the router, wait two minutes.
- Turn on the network devices and computers, one at a time.
This issue is usually caused by resetting a router without resetting all the network connected devices.
Another issue that will cause duplicate IP addresses is assigning static IP addresses to devices that conflict with the router's DHCP address range. If you require static IP addressed devices on the network, they should be configured to be in the same subnet but outside the address range defined for the DHCP server.