There is a server with a KVM on them (Proxmox on Debian).
There are two Debian VMs (not containers).
There is one main IP for the KVM-Host and two additional "single" public IPs.
The idea is to get a virtual network on the KVM, where the single IPs are assigned to the VMs and so they are accessible from the Internet.
KVM-Host should manage the traffic between the VMs, not the Provider's GW.
Сonsultation about the structure of the network is needed.
The system is not critical, so no worries about the data on the server. The main idea to get workable configuration, which can be recreated if the system will be reinstalled or modified (quantitative rather than qualitative). So the task is rather consultancy in the problem solving.