You can get it here https://travel.b-europe.com/dsb-rail/en/reservation-only#TravelWish
according my knowledge these trains are from 26th June reservation compulsory as usually in the summer season.
I think that this overNIGHT must always be REServed-for rather obvious reasons. Its often heavily oversubscribed as its not very long.
You can do the trip overnite but with changes and fairly long waits at either Frederica (fre-retsj) or Padborg-UNreserved as such. But this date is start of general Scandin free for all go on holiday after drunk too much on Midsommerafton.
I think that this overNIGHT must always be REServed-for rather obvious reasons. Its often heavily oversubscribed as its not very long.
You can do the trip overnite but with changes and fairly long waits at either Frederica (fre-retsj) or Padborg-UNreserved as such. But this date is start of general Scandin free for all go on holiday after drunk too much on Midsommerafton.
During the summer there is usually mandatory reservation on all trains between Denmark to Germany. Other times of the year reservation is optional.