Gory South Korean drama "Squid Game" is its number one show in the U.S., and huge around the world.
Now internet service provider SK Broadband says the video streaming firm needs to pay up.
The company on Friday (October 1) announced that it has sued Netflix.
It wants it to contribute to costs from increased network traffic and maintenance work.
SK is streaming 1.2 trillion bits of data a second as a result of "Squid Game" and other hit series.
The legal move comes after a Seoul court said Netflix should give something in return for network usage.
Netflix said it would review SK Broadband's claim, and work with the firm to ensure customers are not affected.
It is South Korea's second-largest data traffic generator after Google's YouTube.
But SK Broadband says the two are the only ones to not pay network usage fees.
It says Amazon, Apple and Facebook are all paying
Netflix data traffic handled by SK jumped 24 times from May 2018, riding on the success of several productions from Korea including "Squid Game" and "D.P."
SK estimated the network usage fee Netflix needed to pay was nearly $23 million in 2020 alone.
