Configure WLAN as metered or tethered in macOS MacOS seems to assume a WLAN connection to be free of charge if and only if it is not a tethered iPhone connection. So it will run all background update and maintenance processes via that WLAN connection. As my WLAN is in fact a small box with LTE access (payed by volume) I would like to configure the connection as if it were a tethered mobile connection, which it really is.

The answers to the similiar question Managing Metered Connections on OSX all recommend some third party tools, how can I solve it solely with built-in functionality and tools (macOS Sierra, if it helps)?
It appears that you cannot without a third party extension.

In this question: How does iOS and OS X detect when a Wi-Fi network is a personal hotspot?

There is an answer that describes how OS X detects whether the connection is a personal hotspot and it seems that there is some meta data that's embedded within the signal that identifies it as a hotspot or not.  (There's even some code that checks for if it's a carplay device, too)


  Apple controls the Hardware, the Drivers and the Operating System, I
  guess they can easily add extra metadata when broadcasting the WiFi
  signal so your Mac knows to whether adding the chain icon or not.