Why your security cameras go offline at night (and what to do)
TL;DR
- Night dropouts scream power/PoE budget + IR current draw + poor network design. Sometimes it’s just cheap cabling.
- Quick wins: verify PoE budget, shorten/replace runs > 100m, lock VLANs/DHCP, and update NVR/firmware.
Symptoms
- Several cameras die after sunset (IR turns on)
- Random reboots; timestamps jump
- NVR shows “disconnected” but pings work intermittently
Root causes
- PoE under-supply when IR LEDs kick in
- Long cable runs or poor terminations
- Switch/NVR firmware bugs, spanning-tree flaps
- Flat networks → broadcast storms, DHCP conflicts
5-minute triage
- Check switch PoE stats: watts/port during day vs night
- Swap one problem camera to nearby port/short patch
- Force camera to day mode (if possible) to confirm IR draw is the trigger
Fixes today
- Move high-draw cams to higher-budget PoE ports (or midspans)
- Reterminate ends; replace suspect copper; keep ≤ 100m
- Isolate cams/NVR on VLAN; reserve DHCP; lock NTP
- Update camera + NVR firmware; disable unneeded services (UPnP)
When to upgrade
- Use PoE+ / PoE++ switches sized for night draw
- Spec starlight/low-lux sensors to reduce IR usage
- Add UPS for switches and NVR
Checklist
- PoE headroom ≥ 25% at night
- All cams on dedicated VLAN; DHCP reservations
- Runs ≤ 100m, certified Cat6
- Firmware current; NTP consistent
