Tellus, pretty much all the common house rules fall under "Your saga may vary."
Especially since the core rulebook does not say that devices CANNOT gain the benefit of arcane connections anymore than it says they can, but they can clearly utilize them via range arcane connection, so there is an interface there somewhere in Hermetic Theory.
No, you are correct saying that devices cannot gain the benefit, to some extent.
First an AC, with respect to penetration, provides a multiplier to the Penetration Ability. Since devices do not have the Penetration Ability, an AC does not multiply anything when used in conjunction with an item.