Very long startup time on Ubuntu Server (network configuration)

Replace your current /etc/netplan/*.yaml file with this, and change enpxxx with the correct name of your second interface...

    # This is the network config written by 'subiquity'
    network:
      version: 2
      renderer: networkd
      ethernets:
        enp4s0:
          dhcp4: true
          optional: true
        enpxxx:
          dhcp4: true
          optional: true

sudo netplan generate

sudo netplan apply

reboot

I was running into this same issue. Similar to heynnema's answer, but more specifically setting the interface to optional allowed the VM to start up (possibly without an IP from DHCP). For instance my netplan config now looks like:

network:
    version: 2
    renderer: networkd
    ethernets:
      ens3:
          dhcp4: true
          dhcp6: true
          optional: true