You can use some network. For example, NAT and Host-only, NAT for external , Host-only for PC.
https://www.virtualbox.org/manual/ch06.html
| Modes | Guest → external | Guest ←→ Guest | Host PC → Guest |
|---|---|---|---|
| Bridged networking | OK | OK | OK |
| Network Address Translation (NAT) | OK | NG | NG (OK : Portfoward) |
| NAT Network | OK | OK | NG (OK : Portfoward) |
| Host-only networking | NG | OK | OK |
| Internal networking | NG | OK | NG |