Hello   @goban 

1. After camera being linked to home Wi-Fi on Tapo APP (camera first set up require internet access), if internet access is disabled, user could still live stream camera & use SD card recording feature/NVR recording without Internet access.

After certain time the app is closed, Tapo APP sometime requires login tp-link ID again, that moment requires internet. 

Some features of camera are based on cloud service and those require internet access to work, like remote control (stream camera remotely), time stamp update, manual recording, talk feature etc. 

2.   NVR/ NAS recording is based on ONVIF protocol, theoretical that could still work without internet access, it is recommended to double-check this point with third party software support.