This is a long shot, but I wonder whether the issue with unreliable connection to the watch could be due to adb getting confused about which device it should be using. When the problem arises, the command adb devices -l could be used to list the devices that adb knows about. If more than one device is listed (eg, due to more than one watch/phone/emulator/AVD), this is a possibility.
There is a way to specify a default device for adb to use, but there’s no point trying this unless there are indeed multiple devices listed.