Internet Speed and Router

Recently, my internet has been really unreliable and slow, and i'm looking to upgrade. Currently, I have a lynksis old router with Charter as an ISP. However, will upgrading my router make my internet much faster or will it bottleneck because I have a slow ISP? I'm looking at the netgear nighthawk ac1900 dual band router but I don't know if it would work. I have 802.11 b/g/n cards in all my computers and I think the router is a ac router. Because of this, I don't know if the router will work with my b/g/n wifi adapters. Also, I saw that there is the netgear nighthawk ac3200 router that is triband and was wondering if it would be worth the 120 extra dollars to buy that instead. Thanks for all the help; It's greatly appreciated.

Don't mess with wireless its horrible for gaming and things that require internet stability.

What is the bandwidth you are paying for? If you are paying for 50/5 internet a new router will probably help a lot. If you are going to do wireless and you live in a populated area make sure you can use the 5 ghz spectrum. If you are paying for 10/2 or less internet, I doubt a new router will help much.