Great, I think I know why it is not working.
Are you sure you are adding volume-viewer.html at the end of all URLs?
If so, you have a caching issue on your local machine as it should not work either. (just a browser thing)
The way to fix that and have http://192.168.60.177:8080/ to work is by replacing
"trame": {
"cmd": [
"volume_viewer",
by
"trame": {
"cmd": [
"volume-viewer",