I've been back and forth with sqe tech support on this one, and was told to submit it here since even contacting my ISP regarding blocked/filtered ports didn't fix it. We opened the ports requested by SQE support for FFXIV as well, and it continued.

Game was working just fine only a few days ago, it was already linked to my steam account since Feb, it began last week days before this patch.

Tech support says this is connection related, but I've used a different ISP mobile hotspot on the computer this is affecting, and it didn't work either. Laptop runs FFXIV just fine even on the internet supposedly affected. My ISP's tech support says it's not on their end.

I've:
Restarted my router, reset my network, restarted my pc multiple times, flushed my dns, deleted the game, uninstalled and reinstalled the launcher, can't get to reinstalling the game since launcher won't boot, uninstalled and reinstalled steam, connected via ethernet and wifi, used a mobile hotspot of a different isp, troubleshooted internet explorer per support's steps, checked my firewall and completely disabled it at some point, opened port ranges 54992 through 54994, 55006 through 55007, 55021 through 55040. Opened FFXIV_BOOT.cfg to change Bootversioncheckmode to 1. Found no patch folders I could delete, since I've deleted the entire game, and this issue began around a week before 6.1 patch. Disabled all programs in task manager. Checked anti-virus software to omit FFXIV. Tried a VPN.

Date & Time: 4/12/2022 10:31am
Frequency: Always, launcher cannot even boot up. Only on my desktop however, FFXIV works fine on my laptop. They use the same internet provider/connection.
World name: Siren
Character name: Dantisdon Stillforest
Steps:
1. Open FFXIV, whether through desktop or steam
2. Gives [Unable to complete version check
30604
20444
19900
15100]
3. Closes automatically

Connection Specs
- Type of internet connection/provider: AT&T Home
- Modem maker/model number: AT&T BGW210

■ PC Specs
Intel(R) Xeon(R) CPU E5-1620 v3 @ 3.50GHz 3.50GHz
64.0GB Ram
64-bit operating system, x64 based processor
Windows 10

To obtain the system information, open the FFXIV launcher and select Config → System Information → Display.

-=-=-=-=- System Information -=-=-=-=-

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Unfortunately, launcher won't boot up.

PC:
Intel(R) Xeon(R) CPU E5-1620 v3 @ 3.50GHz 3.50GHz
64.0GB Ram
64-bit operating system, x64 based processor
Windows 10

Browser Information
- Name and version of the browser currently in-use: Chrome Version 100.0.4896.88
- Internet Explorer Version: 21H2 OS Build 19044.1586

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