Virtualbox Host on Wireless connection cannot port forward

[Solihul2020]

Hi All

I have trawled the internet looking to an answer for this question but cannot find anything!!

I am running Virtualbox 4.something on a Windows 7 install (laptop) that connects to my router by wireless.
I have sent up a bridged VM for Windows 7 and have an IP for this VM. I can RDP to it I can ping it..but it is not visible in my devices list on my router. This means I can't port forward to the VM.
If I connect the laptop to the router by cable and change the Network Adaptor to the LAN NIC, then the device is visble in my router and I can port forward.
My router has even got a ping tool and can ping the VM fine from the router....just can't see it as a listed device.
Any ideas?

Thanks for your time

Andy (Solihull, West Midlands, UK)