[Bug]: Network issue, no longer possible to access internet from virtual machine and no longer possible access virtual machine from SSH client

[igor2x]

Version

7.1.16

Host OS Type

Windows

Host OS name + version

Windows 11 version 25H2 build 26200.8390

Host Architecture

x86

Guest OS Type

Linux

Guest Architecture

x86

Guest OS name + version

Rocky Linux 9

Component

Network

What happened?

Using VirtualBox 7.1.16 on Windows 11 host. I have many Rocky Linux 9 virtual machines. I access Linux virtual machines from Windows host using SSH client. All of virtual machines have NAT Network set in VirtualBox. Everything works just fine for month or so and then in one of the morning all of the virtual machines loses connection to internet and also I can no longer connect to virtual machines using SSH client. In this case I just reboot Windows host and everything just works perfectly again.

Actually this is no 7.1.16 specific, I have had the same issue for few years and have never bothered to open issue request, because host reboot always solved the issue. But yesterday the same issue appeared, virtual machines no longer could access internet and from host I could not access any of virtual machines. Then I have rebooted host as always, but now I am stuck. This always working work-around solution no longer works. Virtual machines can't access internet and I no longer can access them using SSH client.

I can access virtual machines using VirtualBox Manager GUI instead of SSH client access, which is not perfect, but other way around, virtual machines to access internet I have no other solution.

I have installed latest 7.1.x version 7.1.18 on the host and the same issue issue (virtual machines can not access internet and from host I can no longer SSH to virtual machines). Then I have installed the latest version 7.2.8 and the same issue.

Maybe something else has changed, like some Windows 11 update. This is my working computer and new Windows updates are regularly applied usually at night, so it may be some Windows update or something.

Details:

• When I access virtual machine using SSH client on Windows host I get error: "Network error: Connection refused".
• From VirtualBox Manager GUI if I execute some command to access internet e.g. "sudo dnf update", then it returns error: "Could not resolve host: name_of_the_host_here" which indicates some DNS issue. This is the error I always get, then I used to reboot host and issue disappeared. But not now.
• In VirtualBox Manager I have setup Network - NAT Network - Port Forwarding few years back.

On Windows host I opened Task Manager and in search box I typed in "virtualbox". Then I have started one of the virtual machines and what I see is "VirtualBox NAT Engine" as Windows background process, but in few seconds this process just disappears from Task Manager. I guess this is not normal.

I have also tried to change NAT Network to NAT in virtual machine, then inside virtual machine using VirtualBox Manager, I tried to connect to internet and the same connectivity issue. On this specific virtual machine I have set "Port forward" and tried to access machine using SSH client and connection does not work, the same issue.

P.S. When I start up virtual machine from VirtualBox Manager I see green turtle in the task bar. I can NOT turn off Hyper-V completely, because some of the settings of my Windows host are controlled by sysadmins and can NOT I can't turn them off. It looks like Hyper-V is used nowadays for some security enrichments that sysadmins like to have turned on. I know Hyper-V can cause some issues, but so far for years everything was working just fine (if I ignore occasional Windows host reboot).

How can we reproduce this?

It is always reproducible in my case, but don't know how is it on other machines.

VBox.log
VBoxSVC.log

Did you upload all of your necessary log files, screenshots, etc.?

• Yes, I've uploaded all pertinent files to this issue.