Why do Nintendo Switch Joy-Con controllers lose connection with the console?

Joy-Con connection loss with the console can be caused by both software and hardware issues:

Signal interference — Joy-Cons use Bluetooth, and nearby devices (routers, smartphones) may disrupt the signal.

Low battery — when the controller is nearly discharged, the connection may become unstable.

Attachment problems — in handheld mode, the console rail and Joy-Con contacts can get dirty or worn out.

Outdated firmware — both the console and the controllers receive updates that fix bugs.

Antenna defect (especially in early versions of the left Joy-Con).

What you can do:

Update the Switch and Joy-Con firmware via the Settings menu.

Fully charge the controllers and try again.

Clean the rails and contacts with a dry cloth or cotton swab.

Reconnect the controllers via Settings → Controllers → Disconnect Controllers.

If only one Joy-Con keeps disconnecting, it’s likely a hardware defect — better to contact a service center.