Changing uhttpd (LuCI) listeners breaks 'Advanced Settings' page

Routers
1

Spitz GL3000, fw 4.7.4

By default, uhttpd is configured to listen only on the LAN IPv4 address.
Because I prefer IPv6 whenever possible, I changed my uhttpd listener to listen on all addresses on ports 8080 and 8443 via SSH with:

uci set uhttpd.main.listen_http=8080
uci set uhttpd.main.listen_https=8443
uci commit uhttpd
service uhttpd restart

The uhttpd listener responds fine to connections, and all the LuCI pages work just fine, but the ngnix "Advanced Settings" page produces the "An unknown error occurred" popup.

Tracing the management page activity, it appears that the JSON {"jsonrpc":"2.0","id":11,"method":"call","params":["c4hphwZkee5DFZcPmPBwLjw17tEkPpcc","local-access","get_config",{}]} call is producing an HTTP 500 response.

2

Fixed It!

Instead of changing the listeners, I should have added the internal IPv6 listeners as:

uci add_list uhttpd.main.listen_https=[br-lan IPv6 address]:8443
uci add_list uhttpd.main.listen_http=[br-lan IPv6 address]:8080
uci commit uhttpd
service uhttpd restart