Maybe this has already been proposed, but I haven't learned about it yet.

This idea came to me a few days ago.

The only way we're going to accomplish FTL space travel, is to learn how to
manipulate time within a pocket of space. Some kind of energy field. The
relative difference between time on the inside of this field and on the
outside, will allow the ship to move at a practical speed inside the field,
but will be much faster outside the field.

The major issue will then be aging. The participants in such a flight will
be out of sync with earth once they reached their destination and disabled
the field.

Rick