Cameras not found across VLANs

Cameras not found across VLANs

Symptom

The gateway is online. The cameras are online, reachable from a laptop on their VLAN. But Discover cameras on the Gateways page returns an empty list or only finds devices on the gateway’s own VLAN.

Note

ONVIF discovery uses WS-Discovery, which relies on UDP multicast to 239.255.255.250:3702. Multicast frames do not cross VLAN boundaries by default. This is a network design issue, not a camera fault.

Likely causes

1. Gateway VLAN and camera VLAN are isolated — the expected, standard network behaviour.
2. A router between VLANs does not forward IGMP or PIM multicast.
3. No mDNS or WS-Discovery repeater is installed between the VLANs.

Fix

You have three viable paths. Pick the one that matches your network policy.

Option 1 — Put the gateway in the camera VLAN (simplest)

1. Assign the gateway’s network interface an address in the camera VLAN.
2. If the gateway has two NICs, use one for cameras (trunked into the camera VLAN) and one for uplink to the cloud.
3. Re-run Discover cameras. The gateway and cameras now share a broadcast domain.

Option 2 — Add a multicast relay between VLANs

1. On the router between VLANs, enable a WS-Discovery or mDNS relay (often called “PIM”, “IGMP proxy”, or “Avahi reflector” depending on the platform).
2. Confirm UDP 3702 multicast is permitted in both directions.
3. Re-run Discover cameras.

Caution

Multicast reflectors carry every discovery beacon across your VLANs. That leaks camera presence to any host that can receive multicast. Pair with an ACL that limits the relay to the gateway’s IP only.

Option 3 — Add cameras by static IP (no discovery needed)

1. On the Cameras page, click Add camera → By IP.
2. Enter each camera’s IP address, ONVIF port, and credentials.
3. NovaVMS connects directly over unicast; VLAN routing alone is enough.

This is the right choice when security policy forbids multicast across VLANs.

Verify

1. Option 1 / 2: Discover cameras now returns the camera list within 60 seconds.
2. Option 3: Each manually added camera shows a green dot and a live frame.
3. Cameras stay online for 15 minutes with no red-dot flaps.

If none of this worked

• From the gateway host, run ping <camera-ip> to confirm unicast routing works.
• Capture a packet trace on the gateway filtered for port 3702 during a discovery run. Attach to the ticket.
• See also: Camera does not appear in ONVIF discovery.