@David-TP Thank you for your reply. I tried both ways, with ip address and via DDNS. I specify that I can always access other devices on the network from the outside (DVR recorder for remote surveillance). I just add the port number to the DDNS address, or to the ip address (example " :150"), and I can always access the DVR at any time. While on port :80 no one answers. When I restart the router, it works again (also it is the router that updates the DDNS). But after a few days, I can no longer enter remote management, while no problem for the DVR both via IP and DDNS. The router was not provided by the ISP, but I bought it myself. The ISP is "Wind", in Italy. Thank you very much. Best regards.