Quick Preliminary Checks

1. Confirm the video encoding format. Switch between H.264 and MPEG-4 encoding and re-test access.
   Note: Recorders do not support H.265 encoding for GB28181 transmission temporarily.
2. Verify the stream pulling mode of the platform (TCP or UDP) and check if the recorder supports the corresponding national standard stream pulling format.
   Remark: If the device only complies with GB/T 28181-2011, TCP stream pulling is unsupported. If the platform requests TCP streams under this circumstance, the device will respond by sending streams via UDP. Preview failure will occur if the platform rejects UDP streams.
3. If the above solutions fail, contact the dedicated technical support engineer assigned during system delivery for professional assistance.

I. Troubleshooting on the Device Side

1. Basic Device Status Inspection

• Power & Cable Connection: Ensure stable power supply and the device is powered on. Check whether the network cable is firmly plugged in without looseness or damage.
• Device Configuration: Double-check all GB28181 parameters correctly configured on the device, including Device ID, SIP server address, port number, username and password. These parameters must match the platform settings exactly.
• Operating Status: Check device logs or status indicator lights for abnormal alerts. Many devices use flashing light patterns to signal fault codes.

2. Device Function Verification

• Local Preview Test: Launch preview via the device’s built-in management web UI or client software locally. If local preview also malfunctions, the camera sensor or video encoding module of the device may be defective.
• Supported Capabilities: Confirm the device supports the video encoding formats (H.264/H.265) and resolution standards specified by GB28181. Preview errors will arise if the device cannot match the encoding requirements of the platform.

II. Network Troubleshooting

1. Network Connectivity Test

• Ping Test: Run ping commands from both the device network and platform network to verify mutual reachability. Test if the device can ping the platform IP and vice versa.
• Port Reachability: GB28181 relies on SIP (UDP/TCP 5060) and RTP (UDP) for communication. Confirm these ports are open between the device and platform. Use tools such as telnet or nc for port testing, e.g. telnet [Platform IP] 5060.

2. Network Bandwidth Inspection

• Bandwidth Measurement: Use bandwidth testing tools to confirm sufficient upstream bandwidth for video transmission. Insufficient bandwidth causes stuttering or total preview failure.
• Network Congestion Check: Identify heavy bandwidth occupancy from multiple concurrent devices. Disable idle network equipment or adjust traffic scheduling to stabilize video streaming.

III. Troubleshooting on the Platform Side

1. Platform Configuration Audit

• Device Registration Info: Confirm the device is correctly added on the platform with matching Device ID, IP address and port. Check for duplicate entries or configuration mismatches leading to offline status.
• GB28181 Platform Parameters: Verify SIP server address, port and timeout settings align with the device configuration.

2. Platform Log Analysis

• System Logs: Parse platform logs to locate error records related to device registration and video preview, such as failed SIP handshake or abnormal RTP reception, and troubleshoot accordingly.
• Database Validation: Check the platform database to ensure complete and intact storage of device configuration data without loss or corruption.

IV. Protocol Interaction Troubleshooting

1. SIP Message Capture & Analysis

• Packet Capture Tool: Deploy Wireshark or equivalent packet capture software on network nodes between the device and platform to capture full SIP message flows. Analyze failures during registration or session establishment.
• Message Content Validation: Inspect SIP headers and message bodies to ensure compliance with GB28181 specifications. Focus on correct Device ID and authentication credentials inside registration requests.

2. RTP Stream Inspection

• RTP Port Configuration: Confirm consistent RTP port settings on both ends and bidirectional packet transmission of RTP streams.
• RTP Packet Loss Rate: Analyze packet loss via captured traffic. High packet loss will break video preview. Optimize network environment or adjust device/platform parameters to reduce loss.

V. Additional Troubleshooting Items

1. Firewall & Security Policies

• Firewall Rules: Modify firewall access control lists to allow inbound/outbound traffic for all GB28181-related ports and IP addresses.
• Platform Access Restrictions: Check platform security policies including access control lists and user permission limits that may block device access or video preview.

2. Device Compatibility

• Protocol Version Matching: Ensure the GB28181 version implemented by the device is compatible with the platform. Different manufacturers have slight deviations in protocol implementation; cross-version incompatibility often causes preview issues.