MyFRITZ!App reports "A server with the specified host name could not be found [-1003]"
MyFRITZ!App does not display the MyFRITZ! home page of your FRITZ!Box. When it attempts to log onto the FRITZ!Box, MyFRITZ!App displays the error message "A server with the specified host name could not be found [-1003]".
1 Public IP address required for access
You can only use MyFRITZ!App to access the FRITZ!Box from the Internet if your Internet service provider assigns the FRITZ!Box a public IPv4 address or an IPv6 address when it connects to the Internet.
Important:The FRITZ!Box is only accessible from the Internet over IPv6 when used on a DS-Lite ("Dual-Stack Lite") connection. When DS-Lite is active, the status "IPv4 over DS Lite" is displayed under "Connections" on the "Overview" page of the FRITZ!Box user interface.
You cannot access the FRITZ!Box if the FRITZ!Box obtains a private IPv4 address.
If the FRITZ!Box obtains an IPv6 address in addition to the private IPv4 address, then it is possible to access the FRITZ!Box via IPv6, but not via IPv4.
You can only access the FRITZ!Box via IPv6 if IPv6 connectivity is available. Since not all Internet connections support IPv6 connectivity (for example in many mobile communication networks and wireless hotspots), use MyFRITZ!App to call up www.test-ipv6.com or www.ipv6-test.com on your smartphone or tablet to test IPv6 connectivity. You can only access the FRITZ!Box if IPv6 connectivity is available.