NAT Engine doesn't work with a non-default IP range

[Mikhail Kovalev]

As soon as I execute

VBoxManage.exe modifyvm <vmname> --natnet1 "192.168.100.0/24"

(or with any other IP range other than 10.0.2.0/24), NAT stops working on the VM. In the VBox.log I see that the IP range gets assigned to the interface:

00:00:06.927606 [/Devices/e1000/0/LUN#0/Config/] (level 5)
00:00:06.927608   AliasMode          <integer> = 0x0000000000000000 (0)
00:00:06.927608   BootFile           <string>  = "Debian 12.pxe" (cb=14)
00:00:06.927609   DNSProxy           <integer> = 0x0000000000000000 (0)
00:00:06.927610   ForwardBroadcast   <integer> = 0x0000000000000000 (0)
00:00:06.927610   LocalhostReachable <integer> = 0x0000000000000001 (1)
00:00:06.927611   Network            <string>  = "192.168.100.0/24" (cb=17)

But DHCP client inside the VM still gets the following lease data:

  interface "enp0s3";
  fixed-address 10.0.2.15;
  filename "Debian 12.pxe";
  option subnet-mask 255.255.255.0;
  option dhcp-lease-time 86400;
  option routers 10.0.2.2;
  option domain-name-servers 10.0.2.3;
  option dhcp-server-identifier 10.0.2.2;

Assigning a static IP in the 192.168.100.0/24 network (and static gateway 192.168.100.2) doesn't work either.

I can observe this problems on VirtualBox 7.1.6 and 7.1.6. On 7.0.14 the problem does NOT occur. I did not test the versions in between.

Note that the problem only occurs for the "NAT" adapter type (NAT Engine). Changing the address of a custom "NAT Network" works fine.