time.windows.com is known for it's glitchiness. There are a LOT of PCs in the world using it, which can cause delays in the update. If it continues to fail updates, you could try a different NTP server. ( time.nist.gov is a good one) NTP works on UDP port 123, so make sure there are no blocks in Firewall = check Firewall logs to be sure.
As for cameras on built in POE on the NVR = these will not connect to NTP server - there is no direct path for them to access the Internet. I have always advised for IP cameras = turn off the time and date in the cameras OSD (On Screen Display) and just let the NVR time stamp them. (Time on cams on a built in POE will always 'wander' because they can't connect to NTP servers.) Better to just turn off that display than have a sharp attorney contest your video evidence because of time being incorrect.
That's my two cents.....
Ted