When recently voting to close an off-topic undergraduate question, I saw this screen: with the phrase:
Questions about problems facing undergraduate students are off-topic unless they can also apply to graduate or post-graduate academicians as described in What topics can I ask about here?
Note, however, that this description is absent from the linked help center page. Nor is it at What types of questions should I avoid asking?. We do note that questions that are very specific to one person's situation are not likely to get very far, but we don't outright discourage questions specific to undergraduates.
Some SE sites explicitly discourage certain off-topic questions. Mathematics has a detailed list: https://math.stackexchange.com/help/on-topic
Can we add a section like this to our help center?