Android: Unable To Handle Unknownhostexception [with Retrofit 2, Okhttp3, Rxandroid 2]

I've got an Android app which has been in production for some time. I've received a fatal report to Firebase (log is below) but it's not clear to me how to avoid it next time. I've

Solution 1:

The problem caused a nested Rx call. When I unsubscribed from one Rx call, the nested one still lived and caused the crash.