GNS3 has come a long way since its early Dynamips beginnings. There is no doubt it now offers a feature set that can make multivendor topology setups a reality with the integration of the GNS3 VM. With the large feature set though there is still an incumbent learning path. If setup is not quite right you can often find yourself in a worm hole of troubleshooting, and online forums to fix niggles.
I recently setup a basic network topology outside of GNS3 just using the native capabilities in Virtual Box on a windows workstation. This does offer a good alternative if you just want to jump straight to a required lab.
Home lab containing Cisco CSRs, Checkpoint Firewalls in an HA pair, Windows VM and Kali Linux VM below. These are all run and connected just using Virtual Box
This can be done by making full use of Virtual Box 'Host Network Manager'. This is accessed from via the main menu File option in Virtual Box and selecting the host network manager feature.
Use the Create option to add multiple Host Only Ethernet Adapters. These will be auto assigned /24 networks, and added to you PC as virtual adapters.
