The HDR Fox DLNA sharing function definitely works with a TG585 v7 (running firmware 8.2.7.7). WIth your current setup it should be possible to list remote media files and play SD content, but you don't seem to be getting that far. Unfortunately without custom firmware and/or an on-site networking expert the debugging opportunities are limited.
The SD limitation is because the TG585's WiFi (802.11g) is too slow to stream Freeview HD content; you would need to connect the two HDR Foxes to the router with cables for this to work, or upgrade to
faster WiFi router (you could keep the TG585 for connecting to the ISP, disable its WiFi and plug a
new WiFi access point into it).
Incidentally a web search for "Wii DLNA media player" indicates that you might have been able to configure your Wii to play SD content from your HDR Fox but that the Wii won't manage higher resolutions
and wouldn't have been able to access HD content anyway unless you had installed the CF and decrypted it, so a 2nd HDR (or HD) Fox should have been a good move.
DLNA is the standard by which VLC or HDx Fox can list and play media on a server such as an HDR Fox on which it has been enabled by setting Menu>Settings>System>Internet Setting>Content Share=On, as you obvs have done. Without custom firmware this is the only way to do this.
... You must have set up the access credentials for your Humii to register with your WiFi, ...
Humaxen?