Unable to play today due to Error 90000 (Tonberry)

[Seaox]

Actually I have try many things and I sure it is not about my internet connection.
The last time this happened is on June 20, on June 21 I can login again. Then it happened again today, the same issue.
I cannot login to my account while I can login to my niece account every single time, on the same PC at almost the same moment.
Here is what I do:
1. Login to my account -> Failed
2. Login to my niece account -> Successful
3. Repeat step 1 and 2 for 10 times, got the same result.

Then I just try live chat with Square Enix Support Center, they keep let me check my router, my internet connection, and my ISP. But he cannot explain why I can login to my niece account without any problem at all.
Then i ask them to try login to my account and see if they can do that. They just end the conversation. Which mean they could not help.
Now what should I do.

[Xruptor]

Actually I have try many things and I sure it is not about my internet connection.
The last time this happened is on June 20, on June 21 I can login again. Then it happened again today, the same issue.
I cannot login to my account while I can login to my niece account every single time, on the same PC at almost the same moment.
Here is what I do:
1. Login to my account -> Failed
2. Login to my niece account -> Successful
3. Repeat step 1 and 2 for 10 times, got the same result.

Then I just try live chat with Square Enix Support Center, they keep let me check my router, my internet connection, and my ISP. But he cannot explain why I can login to my niece account without any problem at all.
Then i ask them to try login to my account and see if they can do that. They just end the conversation. Which mean they could not help.
Now what should I do.

Okay so this only happens exactly when you both play right? Otherwise if just one of you is on at a time it works fine correct?

[Seaox]

Okay so this only happens exactly when you both play right? Otherwise if just one of you is on at a time it works fine correct?

No I mean, I have tried login to my own account and it just doesn't work, then I logout from my account and login to my niece account right after that, there is no problem at all.
After that I tried to login to my account for several times, and it failed every time, while I can login to my niece account on the same computer, the same connection right at the same hour and it work every single time.

[Xruptor]

No I mean, I have tried login to my own account and it just doesn't work, then I logout from my account and login to my niece account right after that, there is no problem at all.
After that I tried to login to my account for several times, and it failed every time, while I can login to my niece account on the same computer, the same connection right at the same hour and it work every single time.

Then it definitely sounds like something is wrong with your account. I would contact support and tell them that exactly.