Right joycon not connecting when wireless

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!