Hello, My suggestion is the Re 5 from Cuxhaven to Hamburg via Stade, Buxtehude and Hamburg Harburg. The Re drives to all stops as far as Stade. The S-Bahn Hamburg takes over from Stade. In addition, the driver's cab must be changed in Hamburg so that the journey to the main station can be continued. It is a beautiful route that goes a lot along the water and takes about 1 hour and 30 minutes. It is operated by DB-Start. I hope you enjoy my Post !