UTM on MacOS, trying to remote connect to Win11 VM using iPad works on LAN, but over internet: Failed to connect to SPICE

[Technologist-on-the-Go]

I would like to access the Windows 11 VM running on my 2020 Mac Mini M1 using my iPad Pro 11 M1 (2021). It works without a hitch when both devices are on the same WiFi. However, when I attempt to access this over the internet, I get the error shown in the attached image: "Failed to connect to SPICE...Socket I/O timed out".

I have set up port forwarding on my home ATT modem to my TPLINK AX 11000 WiFi router. After doing that, I can see the UTM remote client on the iPad connects to the UTM interface. It can launch the Win11 VM, but it times out when trying to access the VM's desktop. At that point, the VM is running, but all I really do is to power it off.

I have tried what someone else posted about going to the VM's settings -> sharing -> and changing from SpiceWEBDAV to VirtFS. It is still a no-go. I tried setting the sharing option to "None", but it still gets the same timeout error trying to connect to SPICE.