Good afternoon and thank you for posting on the Final Fantasy XIV Technical Support Forums.

Do you recall anything changing/updating on your PC that coincides with this?

The game will use the Internet Explorer web browser to connect to the internet. Open Internet Explorer, then open the "Tools" setting, go to "Internet Options" and adjust the following settings:
- Under the "General" tab, please delete ALL browser history.
- Under the "Security" tab, please move the slider to the lowest possible settings or no higher than "Medium"
- Under the "Privacy" tab, click “Advanced” and select ‘Accept’ under both First Party and Third Party Cookies.
- Under the "Advanced" tab, please make sure that "Allow software to run or install even if signature is invalid" is CHECKED.
- Make sure that all SSL and TLS (EXCEPT SSL 3.0) are CHECKED. [SSL 3.0 should be UNCHECKED]
- Hit "Apply" to save the settings, and then "OK, to close the Internet Options menu.
- Right-Click on the FFXIV launcher icon and select "Properties"
- Go to the "Compatibility" tab, and change the compatibility mode to "Windows 7"
- Hit "Apply", then "OK" to save the changes.
- Please RESTART your PC now. Once your PC has been restarted, Right-Click the FFXIV launcher icon once more and select "Run as Administrator"

Reset your router by turning it off for a few minutes, then back on.

Make sure your anti-virus/firewall has the appropriate exceptions for Final Fantasy XIV (you can temporarily disable them while you try to connect as well).

Try using a wired Ethernet connection as opposed to a wireless connection.

We hope we can be of assistance in helping you enjoy the exciting world of Final Fantasy XIV!