Low bandwidth first, always. I design asynchronous modules so everything critical works offline or on a phone: downloadable PDFs and audio versions of lectures, captioned videos with transcripts, and no activity that requires a live connection to complete. UDL-wise, multiple means of engagement means students pick the format that fits their situation, not just their learning preference. Also worth auditing your LMS pages on a throttled connection, you catch a lot of hidden barriers that way.