Networking issues after upgrade to 4.2.5

* UTM Version: 4.2.5
* macOS Version: 13.3.1
* Mac Chip: M1

I used to run UTM 4.1.x with two VM: one Ubuntu 23.04 and one Windows 11. In fact, I started with lower versions of macOS, UTM and Ubuntu. Then all updates succeeded without major problem.

Today, I upgraded UTM to 4.2.5 and I now have weird networking issues.

Each VM has one network interface, configured as "shared network". With UTM 4.1.x, the two VM consistently received the following IP addresses each time:
- Ubuntu: 192.168.64.2
- Windows: 192.168.64.3
- macOS host: 192.168.64.1

Now, when I boot the various VM, I get this:
- Ubuntu: 192.168.66.4
- Windows: 192.168.66.3
- and on macOS host: 192.168.66.1

Note the new subnet .66 instead of .64.

I did many restarts of the various VM's and I am positively sure that, at some point, the two VM had two different subnets .65 and .66. At that time, the macOS host had two interfaces 192.168.65.1 and 192.168.66.1. Now, for some unknown reason, only .66 is used. I cannot reproduce the situation with two subnets .65 and .66 at the same time but you can see that the subnet moved from .64 to .66.

EDIT 1: After a couple of hours, my Debian VM now boots as 192.168.67.2, jumping to a new subnet .67.

I see no configuration menu for DHCP in UTM. How does the VM receive its IP address? Is there some embedded DHCP server inside UTM? How do you configure it? How can we get stable IP addresses?

Additionally, there is some new weird behavior in the UTM networking GUI since the upgrade to 4.2.5. I just created a new VM and installed Debian 11. The Debian VM gets address 192.168.66.2.

When I edit the configurations of the various VM ("Modify" menu), I get this on the two older VM which were created by some previous version of UTM (can't remember which one exactly). The GUI is in French.


And the network choices are:


In the new Debian VM, created by UTM 4.2.5, I see this:


You can no longer select the NIC type and the advanced settings.

And the network choices are more limited:


The "Emulated VLAN" and "Host only" options are gone. But they are still present in the older VM.

Can't we use "Host only" interfaces with new VM? Can't we specify advanced settings, with a fixed address for instance?

EDIT 2: The "Modify" window for the older pre-4.2.5 VM Ubuntu and the new VM Debian are also different. The old one had "QEMU" and "Input" options. The new one has "Boot" and "Virtualization" instead. We can no longer have access to the full QEMU command with new VM.

Older VM options menu layout:

New VM options menu layout: