Old torpedo nets offer a simple answer to modern drone boats

Will successful drone-boat attacks bring back torpedo nets at harbor entrances?

They are an obvious practical defense, although modern systems will probably be more elaborate and marketed under a new name.

A low-cost physical obstruction can stop a fast explosive boat without an elaborate weapon. A modern program might add sensors or electrical features and market the result under a new name. Its underlying function would still be that of a torpedo net, showing the continuity between older harbour defenses and present littoral threats.