virtualizing physical IIS box into Hyper-V breaks API, Server 2012 R2

I have a physical IIS server that works just fine but when I convert it into Hyper-V, it seems to break an API I use to activate serial numbers. It just doesn’t seem to connect. Everything else still works however, it booted up fine with no issues, the rest of the IIS services work fine, the website works fine too.

The owner of the API assures there is no changes or anything he can do on his end. When I plug my physical box in again, it starts working again. I previously had a very similar issue when I accidentally changed the subnet from 255.255.255.0 to 255.255.254.0, it started giving me the same errors but I’ve assure that the correct network settings are there this time.

I am not the developer of the application but I do own the server, the developer has been completely useless in providing any help diagnose the issue as well.

If it helps, I am running a cisco router, a sonicwall firewall, for diagnosing this issue I have them both fairly open between me and the API server. I also have another physical server which is a DC AD/DNS/DHCP.

Both physical servers are running Server 2012 R2. The hyper-v host is also running 2012 R2. If it also helps, I have IIS logs of both when the API communication fails and when it passes through although they don’t seem to provide many details.

Any help would be greatly appreciated, or at least a push in the right direction.

Thanks!

EDIT: Also worth noting, I converted the physical machine into VMware using VMware converter, then I used the solarwinds converter to V2V the VMWare image into a hyper-v image.