Depending on your router and the number of devices connected to the hotspot and what those devices are used for, you could run into bandwidth problems (not enough resources to go around, which would slow down everyone connected). In general, what you connect to your side of the router is your business. As long as the bandwidth you are paying for is adequate for your purposes, you can use it however you want. You are likely to find that ten people can't successfully stream different live movies simultaneously on a typical home Internet service, for example, but configuring a hotspot shouldn't affect the charge for your service. Your Internet Service Provider will be happy to upgrade you to a faster service at a higher price if you...