Possible issue with wireless router

I've had a wireless router for a couple of years. It's a Linksys N (sorry, don't have exact model number in front of me). I have my DirecTV receiver, Vonage phone, and PC all hard-wired to it and usually have the laptop, my cell phone, and my wife's Kindle Fire connected via wireless. Until recently, I've had very few issues with it. Over the last several days, I've noticed one wireless devices connected is slow. And if two or more wireless devices try to connect, only the first one will connect. I'm not sure if I'm getting some interference from another source, the router is going bad, or something else. Anyone have any thoughts? Thanks.

 

Have you updated to the latest firmware in the router?

 

I checked and the firmware was up to date. I bought another router and it works fine. The other one must have had some sort of internal issues. The speed on it had slowed down some anyway.