You can view NTOP information from the outside by activating Services >> Traffic Monitoring and then set an External Access firewall rule to Allow All to Destination port 3001.
Then from the outside, you can access NTOP by browsing https://...:3001
- where .x..... is your public IP address.
You can also access NTOP internally by browsing
https://yyy.yyy.yyy.yyy:3001- where yyy.y..... is your endian internal IP address.