To change the DNS settings on your FRITZ!Box, log in to the router's settings, and navigate to the "Internet" section. Select "Permit Access" and then "DNS Server." You can then use your Internet Service Provider's (ISP) DNS server or specify a custom DNS server. Once you've entered the DNS server address, don’t forget to save it, and you can start using the new settings. Changing the DNS settings can impact your internet speed or cause issues with certain websites or services, so I recommend choosing a reliable and fast DNS server backed by a trustworthy VPN like the ones on this list. They also offer separate Smart DNS services.