This was discussed a year ago with no stated resolution.
I loaded Quicken Classic on my new PC running windows 11. The files are all in Windows Explorer, but when I start Quicken, it quickly cycles through loading but after the log in screen it ends up with "Please check internet connection and try again".
I spent two hours on the phone with a knowledgeable Quicken guy trying everything related to bypassing Defender etc to no avail. I tried everything that comes from Googling the problem but have had no success.
I have been using Quicken for decades and it runs fine on my old computer running windows 10.