Yay, VMware Fusion and macOS Big Sur - no longer "NAT good friends" - forgive the double negative and the terrible pun ...

After macOS 11 Big Sur was released in 2020, VMware updated their Fusion product to v12 and, sadly, managed to break Network Address Translation (NAT), as per their release notes: -

VMware Fusion 12 Release Notes

Unable to access port forwarding on a NAT virtual machine, if the traffic is routed through the host IP stack on Big Sur hosts

On Big Sur hosts, if user configures NAT port forwarding in Fusion, the service running in the virtual machine is unavailable on the macOS host using localhost:exposedPort, hostIP:exposedPort, or 127.0.0.1:exposedPort; Port forwarding is also not accessible inside a NAT virtual machine using hostIP:exposedPort.

Thankfully, as of now, with Fusion 12.2.0 this is now resolved: -

VMware Fusion 12.2.0 Release Notes

Resolved Issues

Unable to access port forwarding on a NAT virtual machine if the traffic is routed through the host IP stack on Big Sur hosts

On Big Sur hosts, if a user configures NAT port forwarding in Fusion, the service running in the virtual machine is unavailable on the macOS host using localhost:exposedPort, hostIP:exposedPort, or 127.0.0.1:exposedPort; Port forwarding is also not accessible inside a NAT virtual machine using hostIP:exposedPort.

This issue is now resolved.

I updated this AM, and am now running Fusion 12.2.0 on macOS 11.6 and all is well - my Windows 10 VM happily shares my Mac's connection using NAT, and can tunnel via my Cisco AnyConnect VPN, which is nice ....