A sytem error has ocurred 400. HTTPS System Error

Since today I've been getting this error every time I open the FFXIV launcher. Nothing has really changed in my PC, and I've tried everything. I've found other threads about this error but they are all from more than 4 years ago, and the solutions these threads recommend doing haven't worked for me.
The error looks something like this:
https://i.imgur.com/3fFO7yG.png
I've really been struggling for hours trying to fix this thing, but I can't seem to find the solution.
Please, if someone knows anything about this error, help me. I really love this game and I want to be back playing as soon as possible.
Thanks.

Hello Nekody, Thank you for posting on the Final Fantasy XIV Technical Support Forums

Can you elaborate on the kind of issue you are having?

Please provide:

- Platform (PC, PS4, Mac)
- the nature of the latency
- Type of connection (wired or wireless)
- Other programs running while the game is playing (if any)
- Everything you have tried to resolve the issue

Thank you for playing Final Fantasy XIV! Hope to see you online.

Thanks for answering!
- I play on PC.
- I always have good connection, I never have lag or anything.
- My connection is wired
- I usually have discord running, and sometime I use ACT. I've never had any problem using those programs before so I don't think that's the reason.
- I've tried: disabling firewall, disabling antivirus, reinstalling, resetting my modem, resetting internet explorer configs, restarting PC, using wireless connection and flushing dns with the windows command promt, I also tried other commands like ipconfig /release and ipconfig /renew.
That's all I've tried to do, I don't know if I've done something wrong but after trying all these things, I really don't know what to do, and I don't want to do a system restore when I don't know if it will actually work.

I also have the exact same problem. It started yesterday. Tried all the same things nekody did. On my laptop the launcher works but on my desktop that I need it to run on it doesnt if that helps.

Still what I said in my OP but tested real quick before work this morning and it works now. I changed nothing.

Thank you for the reply Nekody.

The launcher will utilize the Internet Explorer web browser, so adjust some of the following settings if you haven't already:

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, please move the slider to the lowest possible settings or to "Allow All 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"

Additionally, you may want to check that the following ports are open:
▼TCP
54992 through 54994,
55006 through 55007,
55021 through 55040

Your ISP may forward these ports for you.

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

Hello everyone,

Due to no response from the original poster, this thread will be moved to 'Closed Concerns.' If anyone is still having this particular problem, please create a new thread and we will assist you in any way we can.

Thank you for visiting the Final Fantasy XIV Technical Support Forums.