Thanks for the .vbox file. Your guest is Bridged to a network adapter called "enp3s0", and from the notes the guest's IP address is supposed to be 192.168.0.181.
See
Virtualbox Networks: In Pictures: Bridged Adapter, for how Bridged works, and an issue if you're Bridging to Wi-fi.
Confirm that "enp3s0" is connected and has "192.168.0.###" IP range. Use 'ip' or 'ifconfig' to confirm the host's, LAN's, and guest's IP ranges. The guest, host and LAN should all be 192.168.0.###, or the guest should be getting the same IP range as the host and LAN. The guest should be able to ping the LAN's router. If the guest can ping the router and the host, then Virtualbox's network is working. Bonus points if the host can ping the guest.
If you can get to the guest website but only text shows but not pictures, then Virtualbox's network is working and there are configuration problems in your Wordpress website.