Disable all services in Ubuntu 16.04 (and later) causing any internet connection

Given that an IOT device running Ubuntu 16.04, I would like to restrict network or internet consumption. Thus, I am looking for two things here.

1. Identify (& Stop) all ubuntu services causing internet connectivity.(List) I have identified some endpoints that ubuntu tries to connect here.

   a. Whoopsie (Crash reporting)

   b. Changelogs.ubuntu.com (MOTD?)

   c. ubuntu updates

   I would like to know any more such endpoint/services, mostly interested in disabling all of these Ubuntu specific network activity. Please help me Identify such services to be added to the list of services to be disabled.

2. Enable network connectivity for these services only when connected to network which is set as non-metered. ( I am facing issue setting my current modem connection as metered for which I will use separate thread)

NOTE:

1. At this time, my application shall use network. I am just trying to curb all other applications shipped by default from Ubuntu which tries to access internet.

2. Also, I am trying to disable these services and not ufw because, given this is IOT device I would like to stop applications from running than ufw restricting the access.