OS/2, eCS & ArcaOS - Technical > Networking

NAT Network & Host-Only Network

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I'm having problems trying to get OS/2 Warp 4 to communicate with other two other VMs on VirtualBox - Windows NT 4.0 and Windows 2000.

I got Windows NT 4.0 and Windows 2000 to communicate with each other by using two network adapters. The first one is set to NAT Network and the second one is Host-Only Network.

The static IP address assigned to Windows NT 4.0 is (host-only: and Windows 2000 is (host-only:

I have set the IP address for the OS/2 Warp 4 NAT Network IP to and the Host-Only Network to as shown in this screenshot, but when I try to access a Windows NT 4.0 or Windows 2000 VM from the Connections window, I get this error:
"Logon: One or more of your connections failed."

Here's  what I have set up right now:
lan0: AMD PCnet FAST II (Am79C973) - NAT Network
lan1: AMD PCnet FAST II (Am79C973) - VirtualBox Host-Only Network
The tricky configuration is that Host-Only Networks have no default gateway and I have the preferred DNS server set at
How can I get OS/2 Warp 4 to communicate with the Windows NT 4.0 and Windows 2000 VirtualBox VMs with the Host-Only Network adapter? Would I need to check the setup.cmd file in \MPTN\ETC to see what could be amiss here?

Post your thoughts, I would like to hear it! :)
(By the way, I'm gonna continue installing updates one-by-one under Windows NT 4.0 as I had to reinstall the OS earlier this morning.)

Hi ppgrainbow

I seem to recall something about having to set Windows NT4/2000 networking to use a particular setting in order for OS/2 <-> Windows peer networking to work. I'm struggling to remember the exact setting ... something like Use LanMan with a value of 1... Sorry, must be around 20+ years ago.

Maybe that will jog someone elses memory and they will post the exact setting.



Hello there. :)
Getting two or more network adapters to work under OS/2 can be quite tricky. I'm gonna have to check to see what I missed up, because the VirtualBox Host-Only Ethernet Adapter on lan1 is only used to communicate between OS/2 Warp 4, Windows NT 4.0 and Windows 2000 VMs.
I'll probably need to find a way how I can get it to work.

Shouldn't it be enough to have all guests in the same NAT network (I understood that Warp 4, Win NT and Win 2000 are all guests under some host, Linux/Win10/Win11 whatever) ?

I understood that "Host only" is for direct communication between a guest and the host but not between guests.

It should be enough. Host-only is for direct communication between the host and guest. My host OS is Windows 10 22H2.


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