Android - Device offline, Sentry although tries to send

I’m new to sentry and wrote a litte sample-app.
Capturing events works fine, all events are sent so sentry-server.
When I turn off wifi on the android device, events get bufferd on storage, but with every event there is a exception:

AsyncConnection: [sentry-pool-1-thread-5] An exception occurred while sending the event to Sentry.
io.sentry.connection.ConnectionException:

Caused by: java.net.UnknownHostException: Unable to resolve host “sentry.xxxxx.de”: No address associated with hostname

Why does sentry try to send events although the device is offline ?
Any configuration missing ?

Permission ACCESS_NETWORK_STATE is granted