virtualbox.org

I apologize for the very basic question.
In my Virtualbox hosted by a Windows 10 box I have an "Internal Network" with a VM based on OpenWrt acting as a gateway and a Windows Server 2019 VM acting as a Domain Controller and DHCP server.
If I install Windows guest VMs in the Internal Network they get an IPv4 address and the default gateway from the DHCP server and navigate with no problem.
If I try to install a Linux box (either Lubuntu and Fedora) in the same "Internal Network" the guest OS does not get any IPv4 address and cannot navigate.
I attempted to assign a manual IP address with no success.
Is ther any specific setting I must apply to the VMs o to the guest OS?
If I connect the same VMs to the NAT they get an IPv4 address from my home router and they navigate withaout any problem...
How can I solve this issue?
Regards

Please see Virtualbox Networks: In Pictures: Internal Network

There are no special settings that I know of which would prevent a Linux VM from connecting to a Windows domain controller while allowing Windows VMs to connect. I lean towards something in the Linux OS that needs to be told that the network has a (Windows) domain controller on it and act accordingly. What that something is, we'll need for a Linux guru to weigh in on.

FWIW, the Pictures tutorial also has a "Sandbox" section, which covers making a Windows DC on an Internal network, with Windows clients (I didn't try Linux clients, though.)

Many thanks for the answer.
I hope that some Linux guru will help...
Regards

Please start the Linux VM, run ip a and ip r in a terminal, shut down the VM from within the Linux guest OS, and provide the (zipped) VBox.log file from this VM run.

To make things simpler I created a new VM "Lubuntu_199" to install Lubuntu.
The VM is confngured to connect to a local network "Lab001".
On the same local network there are an OpenWrt router and a Windows Server 2019 server acting as DC and DHCP server.
I connected my Lubuntu VM to the Lubuntu .iso file and started it.
If I connect the same VM to the NAT network it gets an IP address from my home DHCP server.
After starting my new Lubuntu VM I get a message saying that the network connection is disconnected.
I include the log file, after removing personal information.
Regards

The VBox.log file doesn't indicate any configuration problem to me. The Linux guest has sent 81 frames and received 0. I'd suggest to use the aforementioned ip commands on the Linux guest and Wireshark traces on all nodes to analyze what really happens.