Networking with host

[wmeyer]

I am on the hairy edge of things outside my knowledge, so please forgive a clumsy presentation.
I have multiple VBox VMs on a single host, and I need each of them to be able to reach a DB server on the host, as well as being able to reach the web and our company servers. I have set up each VM with adapter 1 on NAT, which satisfies the needs for web and corporate connections. And I have set adapter 2 in each VM to use the bridged adapter.
Some of the VMs are running Windows 10, and some are on Windows 7, which adds to the challenge of getting them all working the same.
One of the two Windows 10 VMs -- call it A -- can see the host and can see the other Windows 10 VM. VM B, also Windows 10, can see the host, but not VM B.
VM A can connect to the DB on the host using \\myhost as server name, but for VM B, I must provide the explicit IP address.
Neither Windows 7 VM can see the host, though all four VMs connect easily to a shared folder on the host.

I am sure someone must have conquered this challenge and hope that there may be a web page somewhere which presents steps and a comprehensible explanation for someone who only occasionally needs to interact with network admin. I am not even sure how to ask the right question, which is why I have identified the mix of behaviors above.

It would be great to find an app which would collect all the relevant data, and even better if there were some sort of wizard which could achieve a consistent setup across all the VMs.

Thanks!

[BillG]

I presume this host is running on a LAN (otherwise bridged mode does not work). The vms don't need NAT to access the Internet. They do that directly, just as the host or any PC on the LAN does, through the LAN router. The only requirement that might need a second NIC is access to the company servers. Have you considered VPN or some other direct access method?

Does your local setup work properly with just the bridged adapter? I would be very surprised if it did not.

I have been using bridged mode for all sorts of things over many years and have never found a case where a vm behaves differently from a PC on the same LAN.

[wmeyer]

I do need to connect to corporate servers on a VPN, and that pushed me to NAT. I had used Bridged mode for years, and then one day could no longer connect to the company. NAT was the solution.
Now I am focused on achieving a workable environment on my own desktop machine with multiple VMs running and a local RDBMS server on my host. That is the motivation for my original post. The NAT connection remains, as it is needed for my connection to work, and our IT will not facilitate resolution of issues on employee owned machines.
To your question, my local setup works fine with bridged adapters, except I cannot access corporate systems.

[BillG]

It is basically a Windows quirk that seems to have been in the OS for ages. Windows just is not good at switching adapters to perform different tasks. As you found, performance is patchy. I suspect it has something to do with Windows' complex network types (public, private and domain), each with a different set of firewall rules. I avoid multiple adapters like the plague.

Is there any way of putting the link to the corporate site at the router level rather than at the client? Routers are better at it.

[wmeyer]

Is there any way of putting the link to the corporate site at the router level rather than at the client? Routers are better at it.

Not to my knowledge.

On the host, the VirtualBox Host-Only Network IPv4 IP address is set now to: 10.120.30.42
I have assigned static IP addresses in my VMS:
D2007 192.168.1.180 (Windows 7)
XE7 192.168.1.181 (Windows 7)
Tokyo 192.168.1.182 (Windows 10)
Sydney 192.168.1.183 (Windows 10)

Hosts File Entries
On each VM, in C:\Windows\System32\drivers\etc\hosts, this entry is made:
10.120.30.42 my-host

Results So Far
Tokyo and Sydney are able to ping Host and each other.
Host can ping Tokyo or Sydney
D2007 can ping Host, Tokyo, and Sydney
Host, Sydney, or Tokyo pinging D2007 or XE7 fails.