Last Monday 4th of March, in the middle of the day, Amplitude suddenly stopped receiving events from our iPhone and Android apps. The web integration continues working as normal.

See the “logged in” event below for example. Android (blue) and iPhone (purple) suddenly go to 0 at 4pm UTC-3, while Windows (i.e. web) remains normal. Other events show the same pattern.

When I log what is happening in my own Android phone, I see a `POST https://api.amplitude.com/ net::ERR_CONNECTION_REFUSED` error:

We made no changes on our end anywhere near that time. What could cause this and how can I fix it?