Playback lag is usually caused by the network packet loss or insufficient hard disk performance.
Please check whether the channel has lags when live view via single channel.
A、If the channel has lags when real-time preview, it may be caused by non-full frame rate or the network condition. Please check the frame rate and the network condition.
B、If the real-time preview of the channel has no problem, the playback lag may be caused by insufficient hard disk performance. Please test according to the third step.
Step 2：The analysis of the real-time preview lag is listed as follows：
A、Please make sure the main stream frame rate of IPC has been set as full frame rate.
Step 3：The real-time preview of the channel has no problem，the analysis of playback lag is listed as follows:
A、This kind of situation is likely to be caused by insufficient hard disk performance.
The operations which are related with hard disk read/write would appear lag, such as visiting playback interface and log information etc.
B、The video works well on PC which is downloaded from NVR.
C、If NVR installs many disks, please try to play back video files during different time periods. The time span should be as long as possible. And please make sure the playback files and the playback lag files are not in the same disk. Playback files in different disks are usually without lag.
If it meets the above three points A、B、C, we could remove the corresponding hard disk and replace with a new hard disk.
Step 4：Please provide all the necessary information such as models，versions and specific issue description of NVR and IPC to the technical support.