Provide advise: Connecting up to 250 cellphones to a single machine without an Internet signal

Hello, We are developing a project whereby a single computer is connected (via 8-pin lan) to a router or access point. The computer will have a web browser and will be running a custom website we made. The computer will ultimately be used to host a website where up to 250 devices (laptops, tablets, and smartphones) within range of the router or access point. The computer will NOT be connected to the internet at this time and will be treated as a wireless Intranet. The computer will have the Linux operating system (Ubuntu) on them as well as LAMP (Linux, Apache, MySQL, PHP). The router or access point should support up to 250 concurrent connections and be compatible with Linux usage. Where we need advice: Identifying the hardware components (computer hardware and any router/access point) needed to integrate up to 250 devices to a Linux based computer. We will need more than a description, but rather a link to a product easily obtainable to accomplish the task. The devices should have at least a 300 foot range (about 91 meters) to the computer. We are looking for an 'expert' that can advise us in the above point. If you are not experienced in intranet networking with data sharing from computer to smart phone, please do not apply. Thank you!