I have the same issue, except it’s my left joy-con that never seems to stay connected (and when it does it’s incredibly laggy), but the right one works fine. Waiting on an additional BT adapter to see if that resolves anything (currently using a CSR8510 A10). I tried Weldeh’s solution above but it unfortunately didn’t help. Oddly enough, I can use a combination of a Wiimote + right Joy-Con for upwards of an hour without any issues apart from the Wiimote losing calibration frequently.