On this page
01. Signs of a conflict02. Find the duplicate03. Fix it04. Prevent it05. Related06. A typical scenario07. Common mistakes08. Quick checklist09. Frequently asked questions
Switch the terminal off, ping its IP; if something still replies, that is the duplicate. Give the K40 Pro a unique free address, reserve it in the router and note it.
Key takeaways
- Test by switching the terminal off and pinging its IP.
- Choose an address outside the router's DHCP range.
- Write it down.
- Reserve it in the router.
01Signs of a conflict
- Connection works then fails.
- Ping times out intermittently.
- Windows shows 'IP address conflict'.
- Two devices fight for one address.
02Find the duplicate
- Switch off the K40 Pro (or unplug its network cable).
- Run
ping 192.168.1.201from the PC using the terminal's IP. - If you still get replies, another device owns that IP.
- Check your router's connected-devices list to see what it is.
03Fix it
- Pick a free address outside the DHCP range, such as 192.168.1.201 if the router hands out .100 to .199.
- Change the terminal's IP (steps).
- Update the device in the software.
- Test connection.
04Prevent it
- Reserve the address in the router.
- Keep a table of every static IP.
- Ask contractors not to plug random devices into the office network.
05Related
See device keeps disconnecting for other causes.
06A typical scenario
A new CCTV recorder took 192.168.1.201 and the attendance terminal began dropping. Giving the terminal 192.168.1.230 and recording both addresses stopped the clash for good.
Illustrative example based on common cases, not a named customer.
07Common mistakes
- Assuming the router prevents conflicts.
- Not recording static IPs.
- Using addresses inside DHCP.
- Letting contractors add devices unannounced.
- Rebooting instead of fixing.
08Quick checklist
- Switch off and ping
- Find the duplicate
- Pick a free IP
- Change the terminal
- Update the software
- Record it
09Frequently asked questions
How do I know the DHCP range?
Check the router's DHCP settings page.
Can I use any IP from 2 to 254?
Yes if nothing else uses it and it is outside DHCP.
Will changing the IP delete my data?
No. Users and records stay.
What if the router is managed by the building?
Ask the network admin to reserve the address for you.
This guide is part of our ZKTeco K40 and ZKBio Time.Net series. For the full start-to-finish walkthrough with screenshots, read How to Configure a ZKTeco K40 Pro with ZKBio Time.Net.
ZKTeco and ZKBio are trademarks of ZKTeco Inc. Menu names on the K40 Pro and in the software vary slightly by firmware and software version; where yours differ, look for the nearest match. Qyvea is a ZKTeco reseller and installer in Kenya.
