I just finished doing the video suggestions and it worked for me. The video is blaming the issue on a specific Windows 10 update, but I don’t think that is the case as I’m on Win7. What the video is really explaining is how to get a Korg MIDI port to be 10 or less. I suspect the initial problem of the port being > 10 can result from many things including (but not limited to) Windows updates.
I ended up having to do this twice because I followed along a bit too literally. Basically for every Korg device you have you’ll need to create an alias entry for it. And then in a different section of the Registry you need to assign each of those aliases to the Korg driver. The video uses “midi1” for an alias (and so did I the first time). But what you need to do before hand is use the KORG utility to see which midi port numbers you have available and use one of those. In my case “midi6” was available & worked fine while “midi1” wasn’t & didn’t.
The video zips by fairly fast so be prepared to to pause it frequently to follow along with the Registry navigation. I’d recommend when you get to a needed Registry location you save it as a Registry Favorite so you can easily get back. Watch the whole video but don’t make changes until after seeing the whole thing and creating those favorites. Then you can easily hop around making the changes that are specific to your needs.
FYI this is entirely an issue with Korg’s implementation.