Hi Sithum!

If you are using sutom kali thne it should work outside of the local network, with official kali it will just work locally.
So if you said you are using custom kali then are you logging ig with the root:toor credentials? or with kali:kali?

Can you share a screenshot of the Network settings used in VirtualBox for kali?
Have you run the command apt-get upgrade?

Let me know.
Diego