Hello! I had this same issue. A vital question is: have you done work on this joycon before? (Probably replacing the joystick?) If you have, or even if it has taken a fall or two and you don't mind opening up your controller to poke around, there is a fix that I've found. So, I have replaced a couple of left joycon sticks, because they notoriously suck, and I had to replace my right joycon one later on. I had done the left ones fine so I was cocky and went straight into the right on. There is a key difference though that I didn't notice until I started having connectivity issues: there is a part on the battery chasis on the right joycon that is not on the left. The part is a little plastic chip on the charging side, parallel to the battery. This chip is attached to a curved metal looking bar that has a button node on the end. This button node had come undone without me noticing it even existed when I was pulling the controller apart to put in a new joystick. It took some work to get the button plugged back in (very small, didn't want to use metal tweezers), but once I did and put it all back together, it worked like brand new!!). Now, I don't know for sure that this was the problem, I haven't looked at a schematic for the controller or anything and I don't know what that button node is, but it was unplugged, and the connection issue happened right after I fixed the joystick and when I plugged it back in, the controller connected at a distance with no problem…so I think that it's worth a try for ya. Best of luck!
I have two pairs of joycons, the left side works fine, but both of the right side stopped connecting wirelessly after the latest Switch update. I'm in Thailand so I called the local authorized Nintendo repair center and they said there has been several claim cases of the right joycon not being able to connect wirelessly. They said that they didn't investigate whether the cause of the problem started occurring after the update or not, they simply tested the joycon and gave the customer a new replacement unit that worked fine. Since my warranty already expired, they could not offer me replacement, instead they suggested I emailed directly to Nintendo Japan (email@example.com) to report this issue. Maybe if there is enough emails bashing them, they could quickly release a new update that will fix this problem.
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