Realtek RTL8190 802.11n & SMCWBR14S-N4 CCR Wireless Complications

I'm a complete and total networking noob. I just had our internet upgraded to 20MB DL Comcast high speed cable. There are 3 computers on the network. 1 Wired, 2 Wireless. I'm the only computer savvy individual in the household and I don't know what the problem is.

Comcast supplied us with an SMC wireless router, I did a factory reset and I even tried my old linksys and I still have connectivity issues. I am CONSTANTLY disconnecting from the router even while just browsing the web. I just did for a second while I was typing this up. I'm only about 35-40 feet away from the router, there's nothing to interfere with. My drivers are up to date. A friend told me to make sure I was on the right "channel" I opened up the router admin page and I couldn't find whatever he was talking about.

SMC Networks - SMCWBR14S-N4 Barricade

this is the link to the router comcast provided us.

here is the link to the manual.... http://www.smc.com/files/AJ/MN_SMCWGBR14-N.pdf

I have no idea what to do, I continually disconnect. I go to Speedtest.net - The Global Broadband Speed Test and I range from 2mb-12mb (usually under 5mb though) when it's a 20MB cable connection and only my computer out of the total three on the network are turned on.

Something is definitely not correct in my settings and I can't stand it anymore. I need help figuring out how to deduct and narrow down the problems. I'm 25 and I've had a computer since I was 13... but I've only used wireless for about the past year and a half, these problems are new to me.

Windows says there's problems with DNS server sometimes.

Also, if I try playing a game online sometimes it will be ok (on better days, other days I spike to 5k+ ping and dc)

is this happening on both wireless and wired.

the RTL8190 is the wired connection, what is your wireless card.
my nieghbor issue sort of like yours, he contacted suddenlink and they had to reconfigure it on their end after sending out three techs and they said well its connected right maybe you need to have your computer fixed.