Sorry, you are right - my message was unclear. All my issues were caused by windows firewall. Once I turned that off I had no more reconnect problems with any of my mapped drives. I have windows defender running, same as you. You may want to double check and make sure that WF is turned off...
Cannot reconnect to all mapped drives in W7B I had all the same symptoms you had. I found that the problem was with Windows Firewall. There are about a million settings in there and I have no idea how they work, so I just turned WD off completely and viola, no more connection problems. I...