Sands, who signed for Leiston in February, has joined Vanarama National League North side Boston United after the two clubs agreed a fee.
Prolific striker Sands has recently moved to Spalding in Lincolnshire so it was always going to be difficult with regards to travelling to training and games.
After undergoing a double hernia at the end of last season, Sands was slowly returning to full fitness and beginning to show his undoubted skills notably with crucial goals against Tonbridge Angels and a hat-trick against Farnborough.
Leiston manager Richard Wilkins said on the transfer: "It`s a great move for John and a good deal for the club.
“Although John hasn't really been fit enough to enjoy a decent run of games we have seen glimpses of what he is capable of. It`s a shame he has moved on but it`s clearly for logistical reasons and we wish him well at his new club. I am sure when he is fully fit he will be a big hit at Boston."
Pending the necessary paperwork clearance, Sands should be eligible for Boston's home game with Corby Town tomorrow.