This study problematizes the way teacher–student interactions in higher education change as teachers and students transition from face-to-face to fully online learning. By using a qualitative case study conducted over six months at a Malaysian public university, audio-recorded and observational data were gathered from two instructors and approximately 70 students, including interviews with 10 selected participants. Findings show that face-to-face instruction offered structured guidance, immediate feedback, and rich interaction, which supported deeper engagement and learning. In contrast, fully online environments relied heavily on one-way delivery and asynchronous activities, which maintained access but limited dialogic exchange and self-regulated learning. These results suggest that online learning, while necessary for continuity, is not a complete substitute for in-person interaction, because it risks diminishing comprehension and outcomes related to critical thinking. These insights prompt critical questions about how teacher–student dynamics influence learning experiences and outcomes, particularly for achieving equitable education under Sustainable Development Goal 4. The study underscores the need for institutional readiness, particularly for policies and infrastructure that support effective digital pedagogy, and highlights the importance of teacher training for designing blended, interactive, feedback-rich online environments. It also calls for sensitivity to the cultural–technical interplay that shapes how educators and students navigate digital spaces, by ensuring that technology enhances rather than replaces the social dimensions of learning.