Genymotion Desktop requires an Internet connection to verify your credentials and download the virtual device images. If you are using a restrictive firewall, make sure the following ports and domains are allowed.

Internet connection

Outgoing network access

Outgoing TCP port 80 and 443 on *.genymotion.com
Outgoing TCP port 80 and 443 on *.geny.io

Local network connection

VirtualBox is a hypervisor used with Genymotion Desktop.

VirtualBox

When using VirtualBox hypervisor, Genymotion Desktop must connect locally to the virtual device via the local network. To do so, a virtual host-only network card is created and configured.

If you have a firewall, make sure that you authorized connections to Genymotion Desktop and all its virtual network adapter:

allow genymotion.exe and player.exe to communicate with vboxmanage.exe
allow IP range 192.168.56.0/24
allow connections to local port 5555

QEMU is a hypervisor used with Genymotion Desktop.

QEMU

When using QEMU hypervisor, Genymotion Desktop uses the following local ports to connect to QEMU:

5555 (ADB)
6379 (REDIS)
24297 (Audio)
24810 (Audio)
24800 (Camera)
25000 (Render)
22468 (Render)

Make sure that your firewall allows local connections to these, or all, local ports.