Every device on a network needs a unique IP address. Devices on the same subnet can talk directly; the gateway (usually the router) connects them to other networks and the internet. Phones and laptops usually get addresses automatically (DHCP), but cameras, recorders and controllers should have fixed (static or reserved) addresses so they don't move.
Key takeaways
- Unique address per device, same subnet to talk directly.
- DHCP for laptops and phones; static/reserved for security devices.
- Address conflicts make devices drop in and out.
- Keep an address list.
01The terms
| Term | Meaning | Example |
|---|---|---|
| IP address | The device's address on the network | 192.168.1.64 |
| Subnet mask | Which addresses are 'local' | 255.255.255.0 |
| Gateway | The router that leads to other networks | 192.168.1.1 |
| DHCP | Router hands out addresses automatically | Phones, laptops |
| Static / reserved | Device always has the same address | Cameras, NVR, controllers |
02Why security devices need fixed addresses
The NVR finds each camera by its address. If a camera gets a new address after a router restart, the NVR can lose it. Fixed or reserved addresses keep every device where the recorder expects it.
03Common problems
- Two devices given the same address (conflict): both drop in and out
- Device on a different subnet: can't be reached
- New router with a different range: cameras 'disappear'
- No record of which address belongs to which device
See network device offline and NVR not detecting camera. Never publish your site's internal addresses or passwords.
04Frequently asked questions
Should CCTV cameras use DHCP?
It's better to give them static or reserved addresses so they don't change.
What is an IP conflict?
Two devices with the same address. Both become unreliable until one is changed.
Why did my cameras disappear after a new router was installed?
The new router may use a different address range, so the recorder and cameras are no longer on the same subnet.
