I would date this from about 1860 to 1880 but no way to be sure !! Many cabinetmakers continued using the older style joinery into early 1900 !! The lock has been replaced at some point but that should not hurt the value too much !! Is the carving on the chair crest consistent with the buffet and china cabinet !! Often they would not be identical but just have the same elements !!
Remember France and Germany are side by side so it is not unusual to find the same elements in furniture !! Looking at the dining table and chairs,,they are more in line with what you find in France !! Not unusual to find items from both countries in the same set !! How did you come to own this ??