When upgrading NVR from v3.4.x to v4.x, please be sure NVR firmware is at v3.4.92 170518 firmware and perform system factory default before proceed upgrading NVR to v4.x. Failures have NVR at v3.4.92 and perform system factory default prior to upgrading NVR to v4.x could render NVR inoperable.
Up to 12 MP Resolution
to 4K (4096 × 2160) Output Resolution
Supports Up to 24 SATA Hard Disks
HDD Hot Swap with RAID
Supports Up to 128/256 IP Cameras