Who is responsible if one train on my journey is delayed and I miss my connection as a result?

In general, each rail company (carrier) is responsible for its own section of the journey. If there are delays and you have multiple tickets (separate contracts of carriage), the next rail company on a booked itinerary is not obliged to let you travel with them using the ticket for another train. If this happens, however, the rail companies are usually accommodating to each other and will also let you travel as a customer on an alternative train at no extra cost. However, your seat reservation will no longer be valid in such a case. If you arrive late at your destination due to delays or cancellations, the EU-wide rail passenger rights apply.

For further information, including the contact details of the rail companies' refund centres for passenger rights claims, please visit: https://int.bahn.de/en/booking-information/passenger-rights