Connecting mobile wifi to wireless router

Hello,

I have a sony experia and orange wireless router, and i have tried connecting the wifi on mobile to the router but it doesnt connect, it tries o, but then iteven beofre it connects it says the wifi is disconnected. Apparently, its an old wireless router which only takes a certain number of devices, and thats why its connecting, or so i am told. can anyonetell me if this is true and how to fix the problem?