I think that it may be wise to just to take a step back, and to resolve the issue of the duplicate MAC Addresses. Having the same MAC address used across devices on the same subnet will cause all sorts of issues, not only between the devices, but will also affect the border network. As you mentioned earlier, the setup didn’t really work correctly before, and therefore this may just be a continuation.
So would suggest first sorting this out, and then move on from here.
Perform the following:
- Power off ALL VMs and verify that this is the case.
- from the Edit virtual machine settings for the Ubunto VM in question, select Network Adapter - Advanced... then press the Generate button.
- Take note of the assigned MAC Address, and then press OK.
- Power up the Ubuntu VM, log in, then thoroughly test the network.
- if all works as expected, then go through 'ii', 'iii', 'iv' for the second Ubuntu VM that was mentioned previously, however, when you get to 'ii' make sure that the MAC Address is unique, if not, then just select the Generate button again.
- Do this for each of your VMs in turn, but test and check before moving onto the next one.
