Thank you SE for adding Google Auth support

[worldofneil]

why is FFXIV Launcher so un-reliable with 'One-Time Passwords' compared to Websites I have to log into multiple times per day???

Because it's very specific about the time and only allows the password for the 30 second window you are in. Technically it's more secure, but it doesn't allow for any time skew and increases the potential errors for clients if their clocks are slightly out.

Although other websites will have their own rules, in my experience it's common that anything requiring a one time password would accept the current password, but also the password before AND the password after (so increasing the login window size from 30 seconds to 1 minute and 30 seconds). This is why with other websites you can still submit as password as it's about to change, but with XIV as soon as the password changes, it's instantly denied.

It'd be nice if SE would change their system to do this as well, but I'm just happy they're using a standard authenticator now so I'll live with it. If your password is about to timeout, just wait for it to change first

Edit: Also just adding, whatever software you're using to generate the code might not be looking at the current time and rather generating the password right now and just showing a 30 second timer. The password should be changed at :00 and :30 seconds in the minute, but some software just ignores that.

You can check by loading up your software to generate a code and then also watching the clock. If it changes at anything other than :00 or :30 then the software is wrong and that's why you get the login problems. As mentioned above with other websites this isn't a problem as they accept the passwords that come before/after, but XIV is more picky.