Hyper-V Gen1 or Gen2 for Windows install

[ibjonathan]

I've tried to figure this out but I can't find anything. We are running our 3CX on Win 10 Pro for a small business of 20 or so extensions on a Hyper-V Gen1 VM. It works fine, but with the demise of Win 10, I want to just upgrade to Win 11. However, it seems to do so I need to change the Hyper-V to Gen2. All I can find is that 3CX is not supported on Gen2.
I found there is a Debian install for Gen2 but no Windows instructions. I found some references to people who state they are using Gen2 but nothing official.
Is that correct or is it now supported?

 

[UCSA]

My Hyper-V on Win11 and Server 2022 lets me create Gen1 still

 

[Alphabetic]

https://www.3cx.com/docs/installing-microsoft-hyper-v/

id stick to what is recommended by 3CX until they say otherwise to stay in a supported configuration.

 

[SteveITS]

@ibjonathan I suggest installing Debian instead and restoring your backup...that avoids any Windows VM licensing issues, with easier full version upgrades in the future (no need to uninstall/reinstall/restore). Which from the doc page above says to use Gen 1.

 

[ibjonathan]

Im not as good with Linux but Ill test it and see.
But Im not losing my mind, right? 3cx will work on win11 but just not on Hyper-v. Can I use Windows Server or will that require UEFI and TPM also?

 

[KyriacosS_3CX]

Hi, just installing on Win11 works fine. Under Hyper-V on windows 11 also it should be fine. But nesting Win11 into a Hyper-V also running on Win11 would just be wasting resources.

 

[SteveITS]

@KyriacosS_3CX I believe the concern is, 11 requires a gen 2 VM. Does 3CX support that for Windows, just not Debian?

@ibjonathan If you enable auto updates, a Debian VM is more like an appliance. Same web GUI. And you don’t need an Enterprise license which 3CX has said will be required, nor worry about licensing issues such as the 20 connections, or Business Premium or other virtual desktop licensing to use it in a VM. Recent Server versions have similar requirements to 11. And of course higher costs.

 

[ibjonathan]

Yes, you are exactly correct. There seems to be a lot of confusion here on if 3CX supports Gen2 or not, at least other than the pre configured Debian ISO. Win 10 was ideal for such a small number of users because you don't have to go through all the licensing and CALs Win Server requires. If I can't go to Win 11 then Debian is my only answer without maintaining more hardware. Problem is I know nothing about linux so I can't maintain it myself.
What I can't figure is Windows Server is soon going to require Gen2 and is recommended now, so will 3CX just abandon support for virtualization with windows at that point?

 

[fxbastler]

@ibjonathan
If it's a MS Windows (Server or not) VM with a 3CX then it doesn't matter if it's a Gen1 or Gen2 VM. The 3CX is set up on the running system. There is only a MS VDA licensing problem if it's a non Server VM and you don't have such a MS VDA license for it. A Windows Server VM could be Gen1 VM. A Windows 11 VM should be a Gen2 VM, it's required. In any case it should be a 3CX Enterprise version.

A Debian VM has not such a MS (non-Windows-Server VDA) licensing problem, it would work fine, it should be a Gen1 VM to be supported and a 3CX Pro is usable as @SteveITS already mentioned.

 

[ibjonathan]

The licensing of the host is not my question but it is useful information. It informs my choice as to how to fix the issue but its not the issue. Let me simplify.

I am currently running Windows Hyper-V Server 2019 on an HP server with Windows 10 Pro VM Gen1. This runs 3CX for 20 VOIP extensions.
AS Win 10 is no longer updated, I would like to upgrade to same setup with Win11. BUT Win 11 requires TPM and Hyper-V Gen1 does not support vTPM and secure boot, I must convert to Gen2 VMs. But everything I have read seems to hint at but not outright say 3CX cannot run on Gen2 VMs of any guest OS except for the "prepared" Debian ISO. OR am I misunderstanding and you are saying 3CX enterprise is supported under Gen2 VMs?

There are 3 reasons I am still wondering if this is true or not:
1. While the instructions for Hyper-V here: https://www.3cx.com/docs/installing-microsoft-hyper-v/ say you can only use Gen1 and to avoid using Gen2, it is under the heading Debian on Hyper-V, Prerequisites, and so unclear if it applies to Debian ONLY or is it a prerequisite for Windows as well?
2. This document and most other threads talking about this are a few years old. The directions were last updated in 2023, before Win 10 was deprecated.
3. It doesn't make sense to not support Gen2 as now Win11, and soon all Windows will likely have to be Gen2. And all new Windows versions now recommend using Gen2 even if they do still work on Gen1. https://learn.microsoft.com/en-us/w...-generation-1-or-2-virtual-machine-in-hyper-v

 

[KyriacosS_3CX]

Hi,

On a windows 11 VM 3CX should not be aware if the VM is Gen1 or Gen2 - You can always snapshot your Win10 VM, to the update/upgrade to win11/gen2 and revert if any issue is seen.

 

[fxbastler]

If Windows 11 is to be used the way Microsoft intends, several conditions must be met, which can only be fulfilled by a Hyper V Gen 2 VM. These include GPT partitioning, a usable TPM 2.0 and Secure Boot.

The licensing of the host is not my question but it is useful information.

I am aware that this was not your question. However, I want to reiterate that virtualizing a Microsoft desktop operating system without the proper licensing (VDA) is a clear and obvious violation of Microsoft's licensing terms. There is no support for that and ultimately that's what it's all about.

1. While the instructions for Hyper-V here: https://www.3cx.com/docs/installing-microsoft-hyper-v/ say you can only use Gen1 and to avoid using Gen2, it is under the heading Debian on Hyper-V, Prerequisites, and so unclear if it applies to Debian ONLY or is it a prerequisite for Windows as well?

Based on my very clear explanation in the previous post: the binding of a VM on a Microsoft Hyper-V server to a Gen 1 version applies only to Debian 3CX. As for a Windows 3CX VM, I already mentioned that above, see my previous message.

If it's a MS Windows (Server or not) VM with a 3CX then it doesn't matter if it's a Gen1 or Gen2 VM.
...
A Windows 11 VM should be a Gen2 VM, it's required.

BUT However, yes, there are ways and you can still run Windows 11 desktop operating system on Hyper V in a Gen 1 VM without UEFI, TPM and secure boot - but that would be outside of Microsoft support and their recommended usage to get support - exactly, that's why you've been asking all along

... and soon all Windows will likely have to be Gen2.

... not MS Windows Server.

 

[ibjonathan]

I am aware that this was not your question. However, I want to reiterate that virtualizing a Microsoft desktop operating system without the proper licensing (VDA) is a clear and obvious violation of Microsoft's licensing terms. There is no support for that and ultimately that's what it's all about.

Maybe you are right, but I don't think so. Microsoft defines light sharing/small scale services vs. enterprise as the difference between 20 or less concurrent connections and anything more. See below. But it still doesn't answer my question if the 3CX supports Gen2. I came here already knowing Win 11 needs Gen2, what I still do not know is if 3CX supports Gen2. KyriacosS_3CX said it will probably work and I guess I'll just try it and see.

Windows Client vs Server in Hyper‑V (with Scenarios)​

Feature / Licensing Aspect	Windows 10/11 Pro (Guest VM)	Windows Server (Guest VM)
License Requirement	Each VM needs its own valid Windows 10/11 license (Retail or Volume). OEM licenses cannot be reused in VMs.	One Windows Server license can cover multiple VMs depending on edition (e.g., Datacenter allows unlimited VMs).
Connection Limits	Max 20 concurrent inbound connections (file/print sharing, SMB, etc.).	No hard cap; licensed via Client Access Licenses (CALs) which are per user or per device.
Intended Use	Desktop/workstation OS. Light sharing, dev/test, or peer‑to‑peer services.	Multi‑user, enterprise workloads. Optimized for hosting services, databases, and large networks.
Server Roles	Lacks enterprise server roles (e.g., Active Directory Domain Services, Remote Desktop Session Host for multiple users).	Full server roles available: AD DS, DNS, DHCP, RDS, Hyper‑V clustering, etc.
Virtualization Rights	No virtualization rights included — each VM must be licensed individually.	Datacenter edition includes unlimited Windows Server VMs; Standard edition includes rights for 2 VMs per license.
Support Model	Retail license support via Microsoft; OEM support via manufacturer.	Enterprise support with extended lifecycle, CAL management, and advanced tools.
Best Use Case (License vs Recommendation)	License: Permitted for small‑scale services, dev/test, personal use. Recommendation: Not ideal for production or multi‑user workloads due to limits.	License: Required if hosting production services for multiple users (CALs enforce compliance). Recommendation: Strongly advised for enterprise databases, large‑scale virtualization, and mission‑critical workloads.
Real‑World Scenario	Example: 5 developers connect concurrently to a test database VM for development. This is within the 20‑connection cap, so license‑compliant.	Example: 50 employees access a production database VM. Requires Windows Server with CALs (per user or per device). Windows 10/11 Pro would hit the 20‑connection cap and be non‑compliant for production.

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• Windows 10/11 Pro: Limits are concurrent connections (20 max). Fine for small teams or dev/test.
• Windows Server: Limits are managed via CALs (per user or per device). Required for production workloads with many users.

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What the EULA Says
• The Windows 10 license terms state:
“You may allow up to 20 other devices to access the software installed on the licensed device for the purpose of using the following software features: file services, print services, Internet information services, and Internet connection sharing and telephony services on the licensed device.”

 

[SteveITS]

No virtualization rights included — each VM must be licensed individually

This part is the part referenced above...there are a couple of options, such as licensing the user that uses the VM with 365 Business Premium, or there are other options like the annual VDA subscription license.

 

[fxbastler]

Maybe you are right, but I don't think so. Microsoft defines light sharing/small scale services vs. enterprise as the difference between 20 or less concurrent connections and anything more.

The phrase 'maybe you are right' doesn’t quite capture it. You think you know, but that’s not the same as knowing it. You've already found the right spot for my statement yourself. You also have to license the virtualization. Nothing else is confirmed by your post.

I came here already knowing Win 11 needs Gen2, what I still do not know is if 3CX supports Gen2.

I’ve already described that in enough detail, but I suppose it’s not enough for you.

You opened the post primarily to find out what is required to have a fully supported environment for such a virtualized Windows including the question about Gen 1 or Gen 2 VM. The topic of Windows virtual licensing is also part of that. The number of simultaneous connections may be less relevant in this context.