'Final Fantasy 14's Stormblood expansion has been undermined by denial-of-service (DDoS) attacks from a third party since the start of June, according to Square Enix.
The developer has addressed the issue on its website, saying that the DDoS attacks targeting its North American data centre are continuing to happen and that there isn't a straightforward solution to the issue.
The company explained: "Until now, we have been implementing defensive measures at our own facilities to combat DDoS attacks against our 'Final Fantasy 14' game servers, and have been able to keep the impact to services at a minimum."
Square said that since July, the hackers have switched their focus, moving away from targeting the 'Final Fantasy 14' game servers and towards the ISPs that are required to connect to the data centre.
For the time being, the attacks appear to have been contained, but the company has acknowledged the issue could soon resurface.
In its statement, Square added: "We will seek to strengthen our cooperation with the upper-tier ISPs and continue observing our defenses.
"We sincerely apologize for the inconvenience this may be causing, and ask for your patience and understanding as we work with the ISPs to provide the maximum defense possible. (sic)"