Why doesn't Golang return an error when writing to net.Conn when the internet is down?

Question

go

Hello. Here is part of the client code:

func (e *exchanger) trySendByTCP(data []byte) (done bool) {
  if e.tcpConnection == nil {
    return false
  }
  _, err := e.tcpConnection.Write(data)
  if err != nil {
    utils.LogE("Write to TCP error.", err)
  }
  return err == nil
}

I run on a device that is connected to the server via Wifi.
The problem is that if I turn off the Wifi hotspot, the code runs as if there is internet and everything is sent, although logically it should return err != nil.
What could be the problem? How do I send a confirmation?