VirtualBox (and Windows Update) may create a large number of virtual interfaces, which cause another VPN client (such as SoftEther VPN) to stop working. To solve this problem, I created a script to remove all interfaces at once. The original script is removeGhosts.ps1 with one option added.
Run Windows Terminal or PowerShell as an Administrator, then type:
PS> .\removeGhosts.ps1 -narrowByFriendlyName Virtualbox -regardlessOfInstallState -Force