Troubleshooting

ONVIF Camera Not Discovered

ONVIF WS-Discovery uses UDP multicast on your local network. When cameras don't appear in the auto-discovery list, the cause is almost always a network configuration issue — not the camera itself. This guide walks through every cause and fix.

Quick fix: If ONVIF discovery keeps failing, tap + → Manual Entry in SmartRTSP and enter the camera's RTSP URL directly. Manual entry bypasses the discovery protocol entirely and works with any RTSP camera.

How ONVIF WS-Discovery Works

ONVIF auto-discovery is based on the WS-Discovery protocol. SmartRTSP sends a UDP multicast probe packet to the address 239.255.255.250 on port 3702. Every ONVIF-enabled camera on the same network segment that receives this probe responds with its device information and service URLs.

Because multicast packets do not cross subnet boundaries by default, both your iPhone and the camera must be on the same IP subnet for discovery to work. Several network configurations — VLANs, separate wired/wireless networks, firewall rules, AP isolation — can silently block discovery probes.

Discovery at a glance
UDP multicast
239.255.255.250
Port 3702
Same subnet required

Common Causes & Fixes

1

Subnet mismatch — iPhone and camera on different subnets

The most common cause. Many routers separate wired devices (192.168.1.x) from wireless devices (192.168.2.x) into different subnets, or cameras connect to a NVR on a separate VLAN. UDP multicast does not cross subnets without special configuration.

Fix: Check the IP address of your iPhone (Settings → Wi-Fi → your network → IP Address) and the camera. Both should share the same first three octets (e.g., 192.168.1.x). If they differ, either move both to the same subnet or use manual RTSP entry.
2

Firewall blocking UDP port 3702 or multicast traffic

Some routers and managed switches block multicast traffic between client devices, or have explicit firewall rules preventing UDP port 3702. The block happens silently — SmartRTSP sends the probe but never receives a response.

Fix: Log into your router's admin interface and check for multicast filtering, IGMP snooping settings, or firewall rules blocking UDP 3702. Try temporarily disabling these rules to confirm discovery works, then configure an exception for ONVIF traffic.
3

ONVIF disabled in the camera settings

Many cameras ship with ONVIF disabled by default, or require a separate ONVIF user account to be created before WS-Discovery responses are sent. The camera is on the network but will not respond to discovery probes if ONVIF is off.

Fix: Log into the camera web interface (typically at http://[camera-IP]). Navigate to Network or Security settings and look for an ONVIF section. Enable ONVIF and create an ONVIF user account if required. Common locations by brand are listed in the table below.
4

AP isolation on Wi-Fi networks

Some routers enable AP isolation (also called "client isolation") by default on the wireless network. This prevents Wi-Fi clients from communicating directly with each other, which blocks the multicast discovery packets that ONVIF depends on.

Fix: Log into your router and look for "AP isolation", "wireless isolation", or "client isolation" settings. Disable this option for the network that your cameras and iPhone share.
5

Network isolation behind NVR or PoE switch

Cameras connected to a standalone NVR or an isolated PoE switch may be on a private subnet (e.g., 192.168.254.x) that the NVR manages internally. These cameras are not visible on the main home network at all.

Fix: Connect to the NVR's local management interface (often accessible at a separate IP via browser) and use the RTSP URL the NVR provides per camera, rather than expecting to discover the cameras directly. Alternatively, add cameras to your main router's network via direct connection.

Where to Find ONVIF Settings

Camera Brand ONVIF Setting Location Notes
Hikvision Configuration → Network → Advanced → Integration Protocol Must create a separate ONVIF user
Dahua Setting → Network → ONVIF Enable and add an ONVIF user
Reolink Device Settings → Network → ONVIF Port Enable ONVIF; default port 8000
Amcrest Setup → Network → ONVIF Enable protocol; usually on by default
Axis System → ONVIF Enabled by default; create ONVIF account
TP-Link Tapo Advanced → Camera → ONVIF (newer firmware) Use RTSP URL directly on older firmware
Foscam Settings → Network → ONVIF Settings Enable and set ONVIF port

Manual IP Entry — Always Works

ONVIF auto-discovery is a convenience — it is not required to use SmartRTSP with your cameras. If discovery continues to fail after trying the fixes above, adding cameras manually using their RTSP URL is a reliable alternative that works regardless of network configuration.

1

Find your camera's IP address

Check your router's device list, the camera's web interface, or the camera manufacturer app. The IP is typically in the 192.168.x.x range.

2

Find the RTSP URL for your camera

Look up your camera brand in the camera setup guides or check the manufacturer's documentation. The URL format is typically rtsp://username:password@192.168.x.x:554/stream.

3

Tap + → Manual Entry in SmartRTSP

Enter the full RTSP URL and tap Connect. The camera will be added to your list without needing ONVIF discovery to work.

Frequently Asked Questions

What port does ONVIF WS-Discovery use?
ONVIF WS-Discovery uses UDP port 3702 with multicast address 239.255.255.250. Both the port and the multicast address must be reachable from your iPhone to the camera's network segment. Any firewall or VLAN isolation blocking this traffic will prevent discovery.
My camera is on the same Wi-Fi but still not found
Check these possibilities: (1) ONVIF is disabled in the camera's web interface; (2) the camera requires a separate ONVIF user account; (3) your router has AP isolation enabled, which prevents clients from communicating; (4) a firewall rule blocks UDP 3702. Use manual RTSP entry in SmartRTSP as a reliable workaround.
Can I use SmartRTSP without ONVIF discovery?
Yes. Tap + → Manual Entry and enter the camera's RTSP URL directly. All SmartRTSP features — AI detection, multi-camera grid, alerts — work exactly the same whether a camera was added via ONVIF discovery or manual entry.
Why does discovery work on Android but not iPhone?
iOS applies stricter multicast handling than Android in certain network configurations. If your router separates the wireless and wired interfaces, iOS multicast probes may be filtered before reaching wired cameras. Ensure both devices are on the same subnet, or use manual RTSP entry in SmartRTSP.

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