To disable the automatic "Navigationshilfe" search page when misspelling a domain name, it must be deactivated at the Telekom website.

Visit the following link, https://kundencenter.telekom.de/kundencenter/kundendaten/navigationshilfe/ and log in with your Telekom account information.

Simply choose the "Navigationshilfe aus" option and save using the "Speichern" button.

Telekom Navigationshilfe options

You must now restart the Telekom router for the changes to take affect. Either hold the restart button, or simply disconnect the power for a few seconds.

After the router restart, Navigationshilfe will no longer bother you.