If the Virtualbox guest clock lags behind the host’s clock (for example, after a host suspend/resume cycle), you can use the following command to lower the threshold for a forced time synchronization to 5 seconds:
VBoxManage guestproperty set VM_NAME "/VirtualBox/GuestAdd/VBoxService/--timesync-set-threshold" 5000
Change “VM_NAME” to your VM’s name as shown in the GUI. If the name contains spaces, you have to wrap it in double quotes.
If the guest utilities are installed on the guest, Virtualbox should reset the guest clock as soon as the time difference to the host’s clock exceeds 5 seconds.