Square Enix has attributed the connectivity issues that have plagued Final Fantasy 14's Stormblood expansion since its release in June on continuous distributed denial-of-service (DDoS) attacks from a third party. In an update on the company's website, the developer said the DDoS attacks targeting its North American Data Center have shown no signs of stopping and are getting increasingly difficult to contain.

DDoS attacks involve bombarding a targeted network with fake traffic in an attempt to cripple and knock the company's server offline.

"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.

Since July, however, Square said hackers have shifted away from targeting the Final Fantasy 14 game servers to focus on the upper-tier internet service providers (ISPs) required to connect to the data center.

"These attacks to the upper-tier ISP network are causing lapses in communication to the game servers, giving rise to instant disconnects during logins," Square said. "Because we can no longer combat the situation on our own, we have been in contact with the upper-tier ISPs, who have then been taking defensive measures sequentially on their end."

For now, Square said the attacks seem to have been contained through the ISPs' defenses. However, the company warned that the attacks could pop up again.

"Therefore, we will seek to strengthen our cooperation with the upper-tier ISPs and continue observing our defenses," the developer said. "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."

Square has not specified details about the perpetrators behind the attack. No hacker groups have claimed responsibility for the attacks so far.

DDoS attacks have been an increasingly common and frustrating issue for many companies, particularly in the gaming sector.

Blizzard's servers were hit with a slew of DDoS attacks last year claimed by hacking collectives Lizard Squad and PoodleCorp. EA's Battlefield 1 servers, Rockstar Games' Grand Theft Auto Online servers and Niantic's Pokémon Go servers have also been hit with DDoS attacks in the past as well.