Yes. H.265 reduces bitrate but is harder to decode. Some NVRs lower the playback channel limit when recording in H.265. If you encounter the error, try switching recordings to H.264 (if acceptable storage-wise).
Remote apps like Hik-Connect or iVMS-4200 occupy "slots." If multiple users are viewing different cameras, or if you have the app open on several devices at once, you may hit the connection limit. hikvision maximum number of channels under playback reached
All cameras move in time together (Harder on the CPU). hikvision maximum number of channels under playback reached
The most effective "quick fix." Restarting the NVR/DVR releases all hung network connections and clears the decoding buffer. hikvision maximum number of channels under playback reached