So I know you are here because you get this error message while starting a Genymotion Device.
First you should go check your firewall settings as suggested in the Genymotion FAQ. Other than that, if the problem still persist, 9/10 it’s the problem of your Host-only adapter settings. Here’s how to correctly set it.
1. Open VirtualBox, Go to File-> Preferences…
2. Network -> Host-only Networks, you should see 1 item (if there’s none, create one)
3. Follow this settings
4. Select your VM -> Settings -> Network -> Disable the Network Adapter (It will be re-configured by Genymotion)
5. Start the Android Image again in Genymotion UI (not in Virtualbox), It should work now!
You can ask me for help if it doesn’t work for you, leave your comment down below and I’ll be replying you soon.