Conclusion

After launching Ubuntu on VirtualBox, I noticed that the network was not working. This turned out to be because VirtualBox requires manual switching between Wi-Fi and wired LAN.

Environment

• Ubuntu-20.04.4
• VirtualBox 7.1.8

Steps Taken for Trouble Shooting

1. Check the current network status

Type nmcli device status.

<network interface> ethernet connecting (getting IP configuration) netplan-<network interface>

lo loopback connected (externally)

It means the connection to wasn’t really connected.

2.Try to reconnect to network

At first disconnect from current network: sudo nmcli device disconnect <network interface>

Then reconnect: sudo nmcli device connect <network interface>

However, the connect command did not respond and the connection failed.

3.Check VirtualBox settings

Attached to: Bridged Adapter
Name: Killer wireless

Additional context: The host machine (the laptop running VirtualBox) switches between wired and wireless connections depending on the situation. At this point, the host was using a wired LAN connection.

As a result, changing the VirtualBox network setting from Wireless to Ethernet (wired) restored the network connection.

Summary: VirtualBox does not automatically detect changes in the host machine’s network, so manual switching is required.