How to set up networking in VirtualBox?

Question

virtual box

Hello!
You need to create such a virtual network: two PCs, a switch, a router

(ignore the inscriptions, I took it from the Internet). The router must distribute the Internet to both PCs.
What network settings should be set on each of the machines? (Nat, network bridge, internal network, etc.)
And what will need to be registered on the machines themselves? (Ubuntu is installed on the PC, Ubuntu Server is on the router)
Help, who can do what?
Thank you very much in advance!

Answer 1

if all this is virtual, then
on the PC - "internal network"
on the "router" - 1 interface "internal network", the second - nat or a bridge
about switch in virtualbox, I did not hear anything.

Answer 2

Help, who can do what?

Elementary: network settings of different VMs (VirtualBox)
Settings can be made in different ways, and their optimality depends on which operating systems you are using.