I fond this and it works. Just put # on the original settings.
# Server configuration
config uhttpd main
list listen_http 0.0.0.0:80
option home /www
option cgi_prefix /cgi-bin
config uhttpd secondary
list listen_http 0.0.0.0:81
option home /mnt/sda1/arduino/www/
option cgi_prefix /cgi-bin
#