chain, irons, connection
鏈 centers on linked metal rings: a chain. The ideas of irons (metal restraints) and connection grow naturally from that same linked-metal image.
鏈 combines 金 (metal) with 連 (link, connect), suggesting metal links or a chain. The component 連 likely also contributes the sound レン.
The left side is metal 金, and the right side is 連 (link, connect). Picture metal links connected together: 鏈 is a chain.
For レン, imagine a chain made of metal wrenches linked together: wrench -> レン, and the metal chain clinks as you pull it.