When you use MS, when you start up ACNH, hold L to start it without the other addons that might interfere. You mentioned you don't use edizon, which is one of the things you want not loaded, but just in case, might be something there interfering.
Also check the IP address on the MS, I know the default address that shows up isn't the one that I use, I use the one that shows up on my switch when I load up ftpd for example.
Also check the IP address on the MS, I know the default address that shows up isn't the one that I use, I use the one that shows up on my switch when I load up ftpd for example.