Subscribers to British Telecom's BT Infinity Internet service have found themselves unable to access games that use Ubisoft's UPlay DRM, according to numerous Internet reports, and neither BT nor Ubisoft seem to know who's to blame.

Reports of UPlay issues from BT customers first showed up in Ubisoft's support forums last November, before dying down. They picked up again starting Wednesday and continued through to this morning. Many Ubisoft games require players to check in with the UPlay service before starting a game, a process that is for some reason being disrupted for many BT customers, who can't log in to the UPlay client or even load the UPlay website. Other BT subscribers report no problems at all.

Some affected players say that they can get around the problems by using the UPlay client's "offline mode," but others, such as Alec Meer over at Rock Paper Shotgun, have found that the mode doesn't work as it should. Other users have been able to get UPlay's check to work by using a VPN connection to an outside service.

After initially using a (since-deleted) tweet to blame BT for the disruption, Ubisoft now says it's uncertain about the cause of the problem. "If the issue is on Ubisoft's side, then we will of course do all we can to stop it from happening again in the future," Ubisoft forum moderator Lhainiev wrote on the support forums. "If the root of the issue lies with BT Infinity, then there are limits on what we can do to stop future occurrences of the issue, but we will work to identify the options available to us."

BT forum moderator ChristopherP said that his company is "pretty sure that this is not down to a BT network issue," though "investigations are ongoing." BT has recently seen problems with an overzealous porn filter that blocked innocuous programs containing the string "sex" in their names, so it's possible that UPlay has been caught up in a similar dragnet.

This is far from the first time players have run into issues related to UPlay's digital rights management system. In recent years, UPlay has opened legitimate customers up to security risks, made many games unplayable during server transitions and outages, led to misleading explanations of Internet requirements, and even forced Ubisoft to crack its own game to avoid problems.