Connection problems from a netty client in Android - connection

Question

I am using a Netty server in linux with one netty client in Android. (Netty 4.0.23).
It works perfect most of the time. However, sometimes, my client is not able to connect to server.
The ChannelFuture received when trying to connect tells me that connection is done but not success (with cause not null) so it is completed with failure.
About the failure I received it is a java.net.socketException - EHOSTUNREACH error (No route to host).
I am quite sure that the problem is not in server.
Important:
I always run the server and the client in the same lan wifi network
with local ip addresses.
I have tested it in two different wifi
networks. In one of them, the reported error occurs rarely and in the
other occurs quite often.
CONNECT_TIMEOUT_MILLIS is configured with enough time in both contexts
I attach the way I do the connection from client:
.............
final ChannelFuture futureConnection = bootstrap.connect(HOST, PORT);
futureConnection.awaitUninterruptibly();
if (futureConnection.isDone()){
if (futureConnection.isCancelled()) {
// log error
}
else if (futureConnection.isDone() && futureConnection.isSuccess()){
// do something
}
else if (futureConnection.isDone() && (futureConnection.cause() != null)) {
// log error THIS IS THE ERROR REPORTED
}
else {
// log error
}
}
............