May I ask which antivirus you're using? In the past, when this kept happening, it was because I was using McAfee and it simply wasn't compatible with FFXIV on my PC for some reason. I checked settings - making sure FFXIV was being allowed through the firewall etc, all to no avail. However, upon immediately uninstalling McAfee, all was fixed and restored. I decided to get AVG and everything's been amazing a year later, lol. Anyway, this particular problem for me was resolved by uninstalling McAfee and getting a new antivirus software. It may work for you, I don't know.