Here's a good Netflix resource for bandwidth settings
https://help.netflix.com/en/node/87
Adjust your data usage settings
Access your Account page from a web browser and select Playback Settings.
Select your desired data usage setting (please note that each estimate below is per stream, and that restricting data usage may affect video quality):
Low (0.3 GB per hour)
Medium (SD: 0.7 GB per hour)
High (Best video quality, up to 3 GB per hour for HD and 7 GB per hour for Ultra HD)
Auto (Adjusts automatically to deliver the highest possible quality, based on your current Internet connection speed)
Select Save
Note:
It may take up to 8 hours for these changes to take effect.
Data usage settings only apply to the Netflix profile you set them from, meaning you can have different data usage settings for each profile. If you are concerned about the total amount of data that Netflix uses, make sure to change this setting for each profile.
Using the Auto setting is a definite bad idea.