Thank you for answering to my post.

I run FFXIV on/via Steam.
The error message or disconnecting message is "The lobby server connection has encounter an error" with the numbers 2002 on the bottom right of the message box.
I am wired connected but can access WIFI if needed.
The only program I had at start when the issue started was a youtube music playlist that I closed to see if it helped lower the lag (I thought it was my internett at this point but after checking all other program and games ran without any issues and delays/lag)
The lobby disconnection happens every now and then, it happens before I can see the characters on the character screen. Right after I click start when the game has launched.
The lag is on all the characters on Crystal servers for me.

To try fix the issue I have:
-Made sure all my drivers are up-to-date.
-Disabled Windows Defender (temporarily)
-Ran antivirus programs to check for virus, then closed it. (Bullguard) and then check Anti-virus settings for any blockages or network restrictions.
-Adjusted Windows for “Best Performance” rather than quality
-Scanned and defrag all of the drivers, the one where FFXIV is located was prioritised.
-Checked if VPN was active.
-Only ran FFXIV and no other program.
-Disabled Firewall (temporarily)
-Ran FFXIV as Admin.
-Switched power options to high.
-Turned all grapics to lowest setting.
-Tried to run the game in both window and fullscreen.
-Re-installed the game.