Why are ports not forwarded in virtualbox?

Question

virtual box

The bottom line is that I downloaded the backup from firstVds in the qcow2 format. Converted to vdi using QEMU. It has ubuntu with nginx as input.
I'm trying to forward ports in NAT, the screen is in the attachment.

Host - win10.
The IP address of the guest system tried both the localhost and the one that is defined in the ifconfig of ubunta, and the one that is issued in the ipconfig of the host system as the ip of the virtual box adapter.
When you try to access the localhost with port 3000 or 4000, the page takes a long time to load, but in the end it gives an error. If you disable Virtual Box, then the same request gives an error immediately.
Nothing about requests is visible in the error and access logs of nginx.

I myself am not particularly strong in administration, I ask for advice - what to do, where to dig?

Answer 1

Add a host-only network adapter to the guest OS, and make a local network with the host. Immediately from the host, go to the IP address of the virtual machine to the desired port, without any forwarding ..

Answer 2

you just need to ask yourself the question, but can the host and guest have the same network address in this place?
Here is an example of a working ssh forwarding from host to guest..