Thank you for the reply jaaaasssoonnn.

If you are getting the problem on multiple devices, but don't receive the error when using your mobile data, it sounds like the issue lies with your internet connection. I understand that you already contacted them, but if the issue stems from the route you take to the server, you will need to contact your Internet Service Provider. I do have a few suggestions you may want to try to strengthen your home network, but I can't guarantee they will work if the issue occurs beyond your router:

1) Use a wired connection as opposed to wireless.

2) Make sure your anti-virus/firewall has the appropriate exceptions for Final Fantasy XIV.

3) Try a clean boot. Simply open the task manager and select the 'Start up' tab. Disable everything here and restart the PC. This will make sure that no background processes are interfering with the game.

4) Check the following Port Ranges on your router/modem to ensure that they have been opened:
▼TCP
54992 through 54994,
55006 through 55007,
55021 through 55040
Your ISP can open these ports for you.

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