Just bought 2 of these parts to eventually make a server with multiple clients. I have 3 windows 10 machines and I get the same behaviour on all three even though they have very different builds. When I use one device by itself if it picks up com port 1 then it fails to take an upload with com issue. Plug in the second one on the same machine then this gets a different com port. This one is now able to be programmed. Swap the two devices around so that the one that had a sketch uploaded to it now picks up port 1. Now it can’t be uploaded but the other can. Happens on all three machines but the second com port varies. Obviously the two parts are okay otherwise I would not be able to upload to them but only if not on com port 1. The computers are all different with different configurations so it is unlikely to be that. The common element is the device driver so I suspect it is at fault. Tomorrow I will see if I can force a different device to use com port 1 and see if that enables both Feathers to work as they should. I will then also be able to test if I can upload to just one Feather which I cannot currently as the first one plugged in always picks up com port 1. I believe that the resolution of this issue resides with fixing the driver. Is there a less recent driver that might work better? I am currently working with the latest drivers.
It is now the next day and as I suspected when I plug in a different device first so that it gets com port 1 ( I used an FDI232 which gets a com port and USB port), Plugging in the Feather afterwards the first got com port 3 and the second got com port 5. Now both Feathers respond correctly. This is repeatable on another machine, I have not tried it on the third. As I have a work around I need to get on with the project.