Report failed networkj connection in AHC

[ErwanAliasr1]

When running AHC, the benchmark runs and upload to SERV at the end of the run.

But if the upload-check isn't avail or if the IP is incorrect, the benchmark take minutes to run and then fail at uploading ... that's pretty sad waiting so much to know the server isn't available.

We shall check the service is ready before starting the benchmark.