Status. Can be one of the following values:
- 0 Data sent successfully.
- [NRF_EAGAIN] The socket's NRF_SO_SNDTIMEO timeout was exceeded.
- [NRF_EBADF] The socket argument is not a valid file descriptor.
- [NRF_ECONNRESET] A connection was forcibly closed by a peer.
- [NRF_ECOMM] Data transmission failed. Sending may be retried.