Keep having to run SADP to get NVR back online?

[AndyChips]

My HikVision NVR (DS-7604NI-K1 / 4P(B)) keeps going offline - according to the phone app. This happens randomly, but about once a month. The only way to bring it back online is to run the SADP tool and simply click "Modify", even though I've changed nothing.

Whilst offline I've looked at the NVR's Configuration, DDNS settings and the status says "Connect to server failed". No amount of faffing with the settings in that menu brings it back online.

However... if I use the SADP tool the status shows correctly as 'Status of DDNS is normal"

So, I change nothing in the settings but it comes back online after clicking Modify. Why?
What does the SADP tool do that you can't do in the NVR's Configuration, DDNS settings?

 

[AndyChips]

Whoops - what I meant to write above was NOT about DDNS. It was about Platform Access.
The status reverts to Offline until I run SADP.

The question still stands about what this tool changes that you can't see in the Configuration pages.