Ubuntu Server 20.04 VM networking stops working intermittently

**Describe the issue**
I'm running a Ubuntu Server 20.04 VM according to the [setup guide](https://mac.getutm.app/gallery/ubuntu-20-04).

Every so often, the VM networking stops working while it is running. The VM can no longer access the internet, and I can no longer SSH from the host to the VM. The VM console window still works, and I'm able to log in and use the VM that way. I can shut down and restart the VM, and networking works again.

I've noticed that when networking stops working, the CPU usage for QEMULauncher sits at 100%. Nothing inside the VM (checked with `htop`) is using this much CPU.

It happens randomly - I can't reproduce it on demand. I've been running this VM daily for a couple of weeks, and I've seen this issue ~5 times. Once it happened twice (after a restart) within about 5 minutes.

**Configuration**
* UTM Version: 2.4.1
* OS Version: macOS Monterey 12.0.1
* Intel or Apple Silicon? Apple (M1 Max)
* Shared networking

**Crash log**
N/A

**Debug log**
Will add ASAP - sorry, I enabled debug logging earlier, but have since restarted the VM. I'll wait for the issue to happen again and attach the debug log.

**Upload VM**
[config.plist.txt](https://github.com/utmapp/UTM/files/7657264/config.plist.txt)