No site reservation required and access train refused

What is your question?

Which train is this? (route, departure time)

Yes, this happens sometimes-and in some areas now fairly often. Also due to fewer trains run due to shortage of staff.

This is one of the wonders on the INterRail -pass; later you can tell your grandchildren: what granpa has experienced when he was still young………..even worse as that state run SNCF was able to do!

THis is also a hidden incentive to use brains and not just those planners from the web-make plan B.

Until 21/8 you need a reservation on this train.

During the summer there is mandatory reservation on the direct trains between Germany and Denmark. 

Would I be right that the first “reservation” you refer to was entering it into your trip and then into your pass when you activated it, and the pass didn't warn you a separate seat reservation was required. Unfortunately, as you will read all over the community posts, that is not a reservation but just creating a travel ticket. Reservations for trains requiring them need to acquired from other sources.

Note: no train entered into your pass includes a seat reservation - the planner will guide you with reasonable accuracy to those requiring an additional reservation, (but it is always worth looking on the community for tips to avoid these trains)

A quick check on the Interrail planner does indeed show that journey tomorrow does require a reservation, so today’s would have been the same.

Had you known, If you had been at Hamburg early enough you could go to the ticket office and either got a reservation or created a plan B.