If you are recording and viewing live feeds at the same time, the CPU prioritizes recording, leaving less "room" for playback.
Every Hikvision recorder has a specific "decoding capacity." This is the total processing power available to turn compressed data into a moving image. If you are recording and viewing live feeds
Always check your NVR model's datasheet. Look for the "Decoding Capacity" section. It will look like this: Example: 1-ch @ 8 MP / 4-ch @ 1080p. If you exceed these combinations, the error will persist. Update Your Firmware Look for the "Decoding Capacity" section
Hikvision frequently releases updates that optimize decoding efficiency. Ensure both your NVR and your viewing software (iVMS-4200 or Hik-Connect) are on the latest versions. Optimize H.265+ Compression the error will persist.
Entry-level NVRs often support playback of only 1 or 2 channels at 4K resolution, or 4 to 8 channels at 1080p.