Problem with multiple VMs on the same internal network

[Edge97]

Hi! This is my first post here, I don't know if it is in the right category.

I'm using VBox for several years now, and this is the first time I need your help. I'm trying to virtualize a whole LAN to LAN VPN network, consisting in VPN server ( Ubuntu 16.4, intnet "Work") followed by 5 pfSense routers, (router 1: 2 differents intnet "Work" to "WorkWAN", router 2: 2 differents intnet "WorkWAN" to "WAN", router 3: 1 intnet "WAN" & 1 bridged connection to my physical NIC to give internet access to the whole infrastructure, router 4 "WAN" to "HomeWAN" and router 5 "HomeWAN" to "Home" and as the VPN client, another Ubuntu 16.4 VM, on the "Home" intnet.
I've configured all virtual NICs with random MAC addresses, they all are different, all networks are different.
I havent yet configured the VPN.

The problem is occuring every time I switch on the 3 pfSense that have a vNIC in the "WAN" intnet, if i turn on router 3 & 4, I can ping from my VPN client VM all the way to 8.8.8.8 . If I turn router 2 & 3 on, and router 4 off, I can ping 8.8.8.8 from my VPN server VM. But if I turn everything on, I can't ping 8.8.8.8 . And I even can't ping the "WAN" interface of router 3, either from VPN server or VPN client VM's. If I'm on VPN server, the last successful ping is to the router 2 "WAN" interface.

So I decided to log in to router 2 which has 1 vNIC on "WAN" intnet, even from there, if all routers are UP, I have no response from router 3 or on their respective "WAN" interface's IP.

So I've decided to not use router 2 and 4, modified the network properties of 1 and 5 so that they are on the WAN intnet. Thus reducing the infrastructure to "Work" "WAN" and "Home" networks.

Even then, I have exactly the same problem...

Is virtualbox's "intnet" network mode limited to 2 VM's per virtual network ?

Thanks.

Simon

PS: My English isn't perfect, I hope there is not so much faults.
PPS: Tomorrow, I will post/add to this post a Packet Tracer printscreen of my network, It will be way clearer.

[BillG]

That is an interesting problem but I doubt that it has anything to do with VirtualBox. Even if it did, it is much too complex a setup to debug in a forum post, especially without a network diagram of any sort.

Start out small and debug each stage separately. Get all the LAN routing working before you even start on the VPN connections.

Your English is not a problem, but I have no idea what you are trying to do or how you are trying to do it from that description. I can assure you that I have built some complex network setups with virtual machines and virtual networks (including LAN to LAN VPN connections) and have never found a single case where they do not work exactly like the physical model.

I have no idea why you think that you need five routers.