Ask for the missing prompt information. A short connection drop is a technical issue, not a test of whether you can reconstruct facts you never heard.

Continuing with an incomplete objective or constraint creates avoidable downstream errors. It is more professional to clarify immediately.

Say that the connection dropped for a few seconds and ask the interviewer to repeat the last part or the specific section you missed.

Then restate the objective in your own words before starting. This confirms that both sides are aligned.

This came up in one of my mocks and the feedback was basically to stay calm and make the next step explicit.