Most learning platforms are designed in environments where bandwidth is plentiful and stable. Transposed elsewhere, they become unusable: videos that never start, pages that time out, work lost at the first disconnection.
We approached the problem from the other end. The technical target is not the ideal connection but the median one: mobile, intermittent, billed by volume. Anything that does not fit that constraint is reworked until it does.
In practice: text content and exercises take precedence over video, videos exist in low definition, pages remain readable once loaded, and work in progress is kept locally so it survives a disconnection.
This constraint has a useful side effect: it disciplines instructional design. A lesson that cannot be understood without forty minutes of video is often a badly structured lesson.