Due to an unplanned outage of my main ISP, I had to get a mobile data SIM in a hurry, to use as an LTE backup uplink for my Mikrotik hAP ac³ (the whole setup of which I’ll describe one day). Given the price discrepancy of those, I wanted to make every transferred byte count: No unnecessary update fetching or immediate download of high-res sepia-toned photos of bulldogs in tutus.

Android can advertise itself as a metered network to its (Android) clients, so how do I do the same with Router OS 7?

(router agnostic) tl;dr:

1. Make DHCP Option 43 (Vendor-Specific Option) contain the string ANDROID_METERED;
2. The option should be sent even if not requested by the client (not standard compliant, but doesn’t hurt).

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