hi there thank you for the response
This is not a port/firewall issue, as mentioned traffic is being routed correctly
It appears theat Snapcenter uses WMI to collect host data and enumerate the host NICs and is therefore returned the list of the host NICs local IP addresses. Snapcenter then tries to communicate with these, but because they are hidden behind a NAT it cannot and so the add host function fails.
I have proved this now by removing the NAT to the HOST IPs and it all work so as said not a firewall ports issue
Has this kind of setup been tested by Netapp and is it supported, as mentioned this may be a limitation of the underlying technologies used.