Does your Netflix account work on any other televisions?
Strong wifi connection? TV may be loosing its' network connection.
Do you see the TV on the network? Static IP?
Here is fairly comprehensive link that should help you get a stable configuration set up.
https/www.wikihow.com/Watch-Netflix-on-TV
See "Method 2".
Use your Hisense TV's model number to google for the applicable User Guide/Manual.
May be some configuration setting via the TV's menus that needs to be changed/corrected.