Thanks for your response !
The URL http://192.168.8.1/idx_vue.html returns a “Not found” error
I do not know how to access to the directory /var/log/lighttpd/error.log or /etc/lighttpd/lighttpd.conf) when I am connected to SSH. I see no directory at all with command ls. I might do something completely wrong as I am not an expert in Linux, sorry