New Zealand internet users say they have been cut off from United States television streaming service Netflix.
Slingshot spokesman Quentin Reade said the internet provider believed Netflix had made some changes to its systems, preventing access by some New Zealanders.
"Something upstream from our network was changed, that's all I can confirm," he said.
Netflix does not offer its service in New Zealand as it does not have rights to stream its programming here.
It has always attempted to block access using a technique called "geo-blocking", but an unknown number of Kiwis had found ways around the block and subscribed.
Slingshot provides one such option. It introduced a Global Mode service last June that disguises customers' internet protocol addresses so it can appear as though they are in the US.
Slingshot has marketed Global Mode as a free tool that lets overseas visitors continue to access popular online services that are blocked in New Zealand, such as Netflix, but does not police who uses the service.
Fans regard Netflix as a cheap way to watch entertainment programmes that are not broadcast or have their release delayed in New Zealand.
Reade said many of those customers had lost access to Netflix, though Slingshot hoped to restore their service soon.
"Netflix has made a change. I think we have got a solution for many customers," he said.
When Slingshot introduced Global Mode, Telecommunications Users Association chief executive Paul Brislen said he believed it was probably only a matter of time before Hollywood interests responded.
Reade said Slingshot did not know whether Netflix was trying to enforce geo-blocking restrictions and prevent its service being accessed outside North America or whether the issues were unrelated to that possible goal.