Tutorials · PoE
How to Troubleshoot PoE Devices That Won't Power Up or Keep Rebooting
A systematic checklist for cameras and access points that stay dark, flicker or reboot at night.
Before you start
- Access to the switch's PoE status page or CLI
- A cable tester if available
Step by step
Check the PoE standard
The device may need PoE+ (802.3at) or PoE++ (802.3bt) while the port provides only 802.3af. Compare the device datasheet with the switch.
Check the budget
If the total PoE budget is exhausted, new devices will not power up and others may drop.
show poeCheck the port is enabled
PoE may be disabled per port or by a schedule.
Test the cable
Damaged pairs, poor crimps or CCA (copper-clad aluminium) cable cause failures, especially near 100 m. Test or swap the cable.
Check the distance
Standard PoE is specified to 100 m. For longer runs use long-range PoE switches or extenders.
Look for night reboots
If cameras reboot when IR turns on, the budget or per-port limit is too low.
Check for passive PoE
Some devices use non-standard passive 24 V or 48 V PoE that does not work with 802.3af/at switches without an injector.
Replace and compare
Move the device to a known-good port. If it works, the problem was the port or cable.
Commands are generic, industry-standard examples. Exact syntax and menu names vary by model and firmware; check your device's manual on the Documentation page.
Pro tips
- Use solid copper Cat5e/Cat6 cable, never CCA.
- Keep 20–30% PoE budget headroom.
FAQ
Frequently asked questions
Why do my cameras reboot at night?
IR LEDs increase power draw at night. The switch runs out of per-port power or total budget.
Stuck on a step?
Ask Navijin technical support or an authorised partner for help with your configuration.