Your broadband internet connection isn't quite broad enough for what you are trying to do. Netflix streaming will quickly overwhelm that 3mb/s.
Take a look and see if you can get cable internet. It is MUCH faster, and about the same cost as DSL.
Your router is okay. It is wireless N, but it is only N150, meaning single band, single connection etc... N600 routers are pretty cheap these days. Depending on how many devices you are talking about, you may have an improvement in performance by upgrading.
For what it's worth, I stream to 3 devices at once, 2 doing Netflix, 1 doing Youtube, and no slow downs etc...
My network rig is like this...
Comcast Blast 30mb line feeding into a leased modem. About to replace with an owned modem. On the fence between Motorola, and Zoom. Like the Zoom specs better... same price...
Out of the modem, I go into a Cisco / Linksys EA2700 N600 router with 4 gigabit LAN ports. Out of the router I go to a TrendNET 16 port gigabit switch. My wired network feeds into the switch except for my DirecTV LAN connection which goes to the router. I have 1 desktop PC, 1 notebook, a Wii, a PS/3, 2 Android phones, an iPhone, and an iPad talking to the wireless...
Not a single hitch in my internet access speeds that can be traced to my network, or even to the Comcast routers nearest me... When I have lag, I run a traceroute (or tracert in Windows) to the server I am trying to talk to. Typically it is a router on the web, or the destination server that is lagging... Nothing I can do on my side to fix that...
Yes, I can pay more for more bandwidth, but with what I am seeing at this point, there is no reason to even want to. My Linux DVD iso images download in less time than it takes to burn the iso to physical media...
I ran a speedtest.net test on my connection last night, download average speed was 29.88 mb/s, upload was 6.75 mb/s. Considering that my service is advertised at 30mb down and 7mb up I am very happy with it.