As a follow up...

If you are going to uninstall and re-install then make sure you create a backup of your files.  After that, perform a search for Intuit or Quickbooks on your C drive.  Delete all the associated files and folders so that the install does not use any residual files from the previous install.

After you re-install the software do the following:

Reboot the computer

Start QB and login

Attempt to setup the feeds again.  If this does not work then perform the updates and try again.

What I found is that the updates are creating part of the problems which we just stumbled upon when we tried the feeds from a different computer in the office.

Realize this wastes a lot of your valuable time and is frustrating which is why after 24 years of using QB we are done after this year.

Good luck!