The Matter
When a problem comes up, German colleagues name it out loud, plainly and quickly. Germans separate the problem completely from the person. A blunt that is wrong, or this does not work, is aimed at the issue, die Sache, and not at you. Pushing back on the facts is normal and welcomed. Soften a problem too much, hint at it, or wrap it in praise, and you will be read as unclear or evasive. State the problem directly, factually and specifically, and invite the same in return. Disagreement about the matter is healthy, not a rupture in the relationship.
Ownership
In Germany a problem belongs to the specific person with the expertise and the formal responsibility for it, and that ownership is taken seriously. The fastest route to a solution is the right specialist, the Fachmann, or the colleague whose Zuständigkeit it genuinely is. Not whoever is nearest or most senior. Do not expect Germans to jump into a problem outside their lane. That is not my area is a respected boundary, not an excuse. Authority to decide the fix comes from demonstrated expertise in that exact matter, so the deepest specialist often carries more weight than the highest rank.
Definition
German colleagues want a problem pinned down before anyone proposes fixes. What exactly is wrong, under what conditions, and what would count as solved. Expect real time spent on precise definition and on understanding the cause, rather than fast trial and error. This is not foot-dragging. The aim is to get it right the first time, so much of the work happens before any visible action. Push for a quick fix, or for let us just try something, and you will meet resistance until the problem is properly specified. The same rigor can slow things down when a problem cannot be fully defined in advance, so flag genuinely time-sensitive items early and explicitly.
Permanence
When Germans solve a problem they solve it permanently rather than patch it. The complete and durable fix is preferred to the quick workaround, and the solution is written down and turned into the new standard so the same problem cannot return. A recurring issue gets a rule, a procedure or a standard built around it. This is why German solutions take longer to land and then tend to hold. If you propose a temporary fix, be ready to say why it is acceptable as a stopgap and what the permanent answer will be. An open-ended patch feels unfinished.
Self-Image
Germans hold a strong self-image as exhaustively systematic, methodical, root-cause-driven problem-solvers. German engineering. Gründlichkeit as a virtue. It is taught and celebrated, and it is worth knowing, because it tells you what colleagues aspire to and respect. Precision, method, getting to the bottom of things. The reality does not always match the ideal. The same drive for complete and systematic solutions can produce delay, over-process and real difficulty when a problem cannot be planned out in advance, and high-profile German projects have stalled for exactly this reason. Honor the ideal in how you present your own work, and plan for the gap.