Dear Jian
About this issue ,I need some information from your customer
1.The PoE switch brand and model name
2.The NVR brand and model name(with firmware version)
3.Error 3031-C ‘s serial number
The 3031-C 6/2 beta version is about add new function(edge record)
3S web site firmware(2016.07.04) is based on 6/2 beta version, and 7/4 version is pass by a harsh test
So if you can upgrade the newest firmware is better.