This is a slightly difficult problem to explain without same basic background information - I'll try and refine the question later as necessary

Originally, I have a single hosted server (Win 2008R2) with the following range of 8 IP addresses.

- Single NIC
    - IP: x.x.128.72 -> x.x.128.79
    - Subnet: x.x.255.192
    - GW: x.x.128.65

After installing Hyper-V and setting up a single virtual server on the same box, I then wanted to assign one of the IP addresses to the virtual server, leaving everything else running normally.

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Firstly, I tried using the "External" network, but (even after setting IPs on the "Virtual Adapter" similar to Here but struggled to get networking running at all.

I needed to keep the server running (otherwise I would have spent more time pursuing this approach)

Q1 ... Was this a sensible thing to do ? Should I have carried on down this route ?

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I then decided to try different approach - Set the HyperV network to "Internal" (visible to Management OS)

- Physical NIC
    - IP: x.x.128.72 -> x.x.128.75
    - Subnet: x.x.255.192
    - GW: x.x.128.65

- Virtual NIC
    - IP: x.x.128.78
    - Subnet: x.x.255.252
    - GW: x.x.128.72 ... { The same as the IP of the physical NIC )

- Virtual OS-NIC
    - IP: x.x.128.77
    - Subnet: x.x.255.252
    - GW: x.x.128.78 ... { The same as the IP of the host virtual-NIC )

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Surprisingly enough, this approach actually worked, and I was able to connect from all the following: - Internet to/from physical NIC (x.x.128.72) - physical NIC (x.x.128.72) to virtual-OS-NIC (x.x.128.77) e.g. testing via ping + FTP - Internet to/from virtual-OS-NIC (x.x.128.72)

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The problem I have is that this approach seems to only last for a short while (a few hours).

After this time, it seems that I lose the ability to connect from Virtual-OS-NIC to/from the internet (but I can still connect from the host-OS to the virtual-OS and from the host-OS to the internet)

I have re-tested this a couple of times with the same results ... I leave the server on for a few hours (e.g. overnight), and when I come back in the morning, the Virtual-OS loses the ability to route to the internet

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I'm not quite sure what to look at next (or whether I'm going about this completely the wrong way )

One "possible relevant item" is that the host-OS is also running RRAS (Routing and Remote Access), but this is only to run a simple VPN

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Q2 - Wheat should I be looking at next ? (Any good references / recommendations of what to try)

Would appreciate any thoughts or comments (even if you tell me I'm going about this the wrong way)