Recent worldwide reports point towards the left Joy-Con having some issues with connectivity. Some consumers have complained (along with a few well-known gaming websites) that the signal drops off completely if there are any obstructions between the player holding the Joy-Con and the Nintendo Switch. Nintendo have since issued a statement which urges players to remove any obstructions and to keep away from aquariums. Big bundles of wires are a no-no too.
Thankfully YouTube member Spawn Wave has found out a nifty little trick to ensure that connection issues will be no more. By adding a small cable into the left Joy-Con it boosts the signal strength so you won’t have Link falling to his death or standing there aimlessly while a Guardian makes you the next best recipe on Breath Of The Wild.
Check it out below. I’d advise against fiddling around with it myself and to remove your aquariums as it does look a bit tricky: