NAT stops working on traffic between

[pidi]

I experienced the following issue on both my Dedicated Virtual Hosts:

Setup:

1. CentOs6 - 8 VMs (Debian, CentOs, Ubuntu) - VirtualBox 4.3.16
2. CentOs7 - 8 VMs (Debian, Windows 2008R2) - VirtualBox 4.3.18

When I download big files from one VM to another (over http) NAT network stops working and I cant get in anymore (and out as well). It helps to send all VMs in 'save state' and resume them.

My workaround is to provide a selfmade NAT network over OpenVPN by creating a TAP device on the host and add a bridge on all VMs connecting to it.

Note: Both of them are in productive use.

[pidi]

Updated VirtualBox to the current version available, but this issue still appears. Is there a log not for the vms but for virtualbox itself?

[Valery Ushakov]

Do you use NAT or NAT Network?

If you need two VMs talking to each other, you can use Internal Network.