PHILADELPHIA -- EarthLink Inc. is pulling the plug on its troubled wireless high-speed Internet network in Philadelphia, once touted as a model for how big cities should deploy Wi-Fi. The Atlanta-based Internet service provider said that it could not find a buyer for the $17 million network and that talks to give it to either the city or a nonprofit organization had failed. City officials have said it would cost taxpayers millions each year to operate the network. Philadelphia officials recently said they wanted EarthLink to abide by the contract, but would rather not go to court to enforce it.