Your friend is not hosting a server and they are not incurring damages due to having trouble connecting to the internet.
The damages from not being able process legitimate requests is like if you DDoS an ecommerce site which means that they are unable to receive orders from legitimate customers which causes them damage.
> The CFAA broadly38 defines “computer” as any “electronic, magnetic, optical, electrochemical, or other high speed data processing device performing logical, arithmetic, or storage functions,” including “any data storage facility or communications facility directly related to or operating in conjunction with such device . . . .”39 The CFAA excludes only automated typewriters, typesetters, portable hand held calculators, and similar devices from its definition of computer.40 These limited exceptions to the CFAA’s definition of “computer” “show just how general” the statute’s definition of computer is.41 As one court explained, the definition includes any device with an electronic data processor, of which there are numerous examples.42 Thus, under the CFAA, computers include not only laptops and desktops, but also a wide array of computerized devices ranging from cellphones to objects embedded with microchips, such as certain microwave ovens, watches, and televisions. 43
The definition is extremely broad; which means it also includes things like modems and routers.
But they are, right? Whoever is hosting the multiplayer match is running a server. And damages come in the form of being rendered unable to enjoy the video game they paid money for. "Damages" do not have to come in the form of lost customers.