First of all, I have to admit, I love VirtualBox. Because of VirtualBox I made my employer save about $10,000 in software and hardware purchases (server hardware and server software).
A co-employee of mine from my sister's company called me about his laptop because the installed guest OS on his VirtualBox was not able to connect to the network.
I was caught off-guard
I frequently use VirtualBox on desktop that only has a single Ethernet card or network card. I was troubleshooting the network problem of the guest OS on the laptop but I couldn't fix it at first try.
But an idea suddenly popped-up on my head. What if the laptop is using the wireless network card rather than the wired network card?
My co-employee is using the wired network connection not the wireless connection
As it turns out, I was correct. I immediately changed the settings of the VirtualBox to use the wired network card over the wireless network card and voila, the problem is fixed.
How the problem happens
As it turns out, when you install a VirtualBox on a laptop it uses the wireless network connection as the default network card.
So, if you are accustomed in using VirtualBox on a desktop that only has one network card you might not going to bother on changing the default network card.
On a desktop that has only a single network card it will use that network card by default. But not on a laptop, you might think that the laptop's wired network card will be used as a default then you are wrong.
When I began troubleshooting the problem I was only thinking about the wired connection of the laptop since it is the one being used by the laptop.
I forgot that a laptop usually has two connections, a wireless connection and a wired connection.
So, whenever you install a VirtualBox on a laptop make sure change the default network connection of the VirtualBox into the wired network connection since VirtualBox uses the wireless network connection by default after installation.