Q:

Start job is running for wait for network to be configured. Ubuntu server 18.04

I am receiving the message "Start job is running for wait for netowrk to be configured" during bootup.  Computer hangs for 2 minutes until whatever is going on times out. Network connection appears to be there since there appears to be a successful synchronization to time ntp.ubuntu.com just prior to the hang.
This is within VirtualBox, after setting Adapter 1 to NAT, Adapter 2 to Host-Only Adapter, and setting /etc/netplan/50-cloud-init.yaml as follows:
network:
    ethernets:
        enp0s3:
            addresses: []
            dhcp4: true
        enp0s8:
            dhcp4: true
    version: 2

(I'm new to netplan; admittedly I'm poking in the dark here).
Reviewing syslog after bootup, here is what I see:
Nov  6 22:55:47 magnolia systemd-networkd[539]: enp0s3: Gained IPv6LL
Nov  6 22:55:47 magnolia systemd-networkd[539]: enp0s3: Configured
Nov  6 22:55:47 magnolia systemd-networkd-wait-online[546]: ignoring: lo
Nov  6 22:55:47 magnolia systemd-networkd-wait-online[546]: managing: enp0s3
Nov  6 22:55:47 magnolia systemd-timesyncd[423]: Network configuration changed, trying to establish connection.
Nov  6 22:55:47 magnolia systemd-networkd[539]: enp0s8: Gained IPv6LL
Nov  6 22:55:47 magnolia systemd-timesyncd[423]: Synchronized to time server 91.189.89.199:123 (ntp.ubuntu.com).
Nov  6 22:55:47 magnolia systemd-networkd-wait-online[546]: Event loop failed: Connection timed out
Nov  6 22:55:47 magnolia systemd[1]: systemd-networkd-wait-online.service: Main process exited, code=exited, status=1/FAILURE
Nov  6 22:55:47 magnolia systemd[1]: systemd-networkd-wait-online.service: Failed with result 'exit-code'.
Nov  6 22:55:47 magnolia systemd[1]: Failed to start Wait for Network to be Configured.
Nov  6 22:55:47 magnolia systemd[1]: Starting Initial cloud-init job (metadata service crawler)...
Nov  6 22:55:47 magnolia cloud-init[587]: Cloud-init v. 18.4-0ubuntu1~18.04.1 running 'init' at Tue, 06 Nov 2018 22:55:46 +0000. Up 128.51 seconds.
Nov  6 22:55:47 magnolia cloud-init[587]: ci-info: ++++++++++++++++++++++++++++++++++++++Net device info+++++++++++++++++++++++++++++++++++++++
Nov  6 22:55:47 magnolia cloud-init[587]: ci-info: +--------+------+-----------------------------+---------------+--------+-------------------+
Nov  6 22:55:47 magnolia cloud-init[587]: ci-info: | Device |  Up  |           Address           |      Mask     | Scope  |     Hw-Address    |
Nov  6 22:55:47 magnolia cloud-init[587]: ci-info: +--------+------+-----------------------------+---------------+--------+-------------------+
Nov  6 22:55:47 magnolia cloud-init[587]: ci-info: | enp0s3 | True |          10.0.2.15          | 255.255.255.0 | global | 08:00:27:c9:60:26 |
Nov  6 22:55:47 magnolia cloud-init[587]: ci-info: | enp0s3 | True | fe80::a00:27ff:fec9:6026/64 |       .       |  link  | 08:00:27:c9:60:26 |
Nov  6 22:55:47 magnolia cloud-init[587]: ci-info: | enp0s8 | True |        192.168.56.105       | 255.255.255.0 | global | 08:00:27:41:62:12 |
Nov  6 22:55:47 magnolia cloud-init[587]: ci-info: | enp0s8 | True | fe80::a00:27ff:fe41:6212/64 |       .       |  link  | 08:00:27:41:62:12 |
Nov  6 22:55:47 magnolia cloud-init[587]: ci-info: |   lo   | True |          127.0.0.1          |   255.0.0.0   |  host  |         .         |
Nov  6 22:55:47 magnolia cloud-init[587]: ci-info: |   lo   | True |           ::1/128           |       .       |  host  |         .         |
Nov  6 22:55:47 magnolia cloud-init[587]: ci-info: +--------+------+-----------------------------+---------------+--------+-------------------+

I find it curious the timestamp doesn't reflect the 2 minute wait, but perhaps that's another question.
I found this other answer for Ubuntu 17, appears to be related:
A start job is running for wait for network to be configured. Ubuntu server 17.10
and tried disabling systemd-networkd-wait-online.service as indicated but that does not appear to work (still get the 2 minute wait).
Any ideas what's going on here, and how to fix it?  

A:

Notes: 

Undo your previous fixes. Return them to the original state.
You may be having a problem obtaining IPv4 addresses.
In setting up your VM, you set "Adapter 1 to NAT, Adapter 2 to Host-Only", and I'm not sure that's 100% correct... However, if you're getting the correct IP addresses then it's probably OK.

Try this in your /etc/netplan/50-cloud-init.yaml...
network:
  version: 2
  renderer: networkd
  ethernets:
    enp0s3:
      dhcp4: true
      dhcp6: false
      optional: true
    enp0s8:
      dhcp4: true
      dhcp6: false
      optional: true

In the terminal, run the following...

sudo netplan --debug generate
sudo netplan apply
reboot

