An easy way to test if it is your router is to remove it and see if the problem goes away too. Take the cord coming from your modem that the Internet Service Provider (ISP) gave you and plug it directly into your computer instead of going to the WAN port on the router. If it still has issues, then it is the router. And that wouldn't necessarily mean the router is "broken" but it could just be missconfigured (i.e. has some settings not properly set).
The router is only 2 years old, it should still be fast enough to play games on. Is anyone else using the connection when you try to game? Do you have it password protected with WPA2 so no neighbors can "leech" your signal? If you remove the router and it still goes very slow and choppy, you need to contact your ISP. Good speeds on speedtest.net does not mean your internet connection is good for gaming. There are so many factors involved (Download/Upload speed, physical location of the game server you connect to, latency, network saturation, etc) and your ISP is in the best position to help you evaluate what the problem is if you find the router is not the problem.
Thanks for the help.
I do have someone on the internet sometimes when I play games, but most of the time it is just me using the internet. I live in Canada which is usually as bit far from the servers I connect to, but that shouldn't be a factor considering this problem only came about recently. I will try and connect it directly and see if that fixes it. If ti does, I'll clear your answer as a solution.