Your connection speed is 54Mbps so you're probably connecting with the 802.11g protocol.
Then the 3MB/s is the expected speed. Ideally you would get to around 3.5MB/s but that would be the absolute maximum.
Have a look at this site.
There ~20Mbps downstream is mentioned. (just ~2.5MB/s)
Please note the difference in Mbps (Mega-bit/s) and MB/s (Mega-byte/s).
Your 3MB/s is (x8) 24Mbps.
You can also look at this answer. It has some lovely technical explanations.
In real world conditions I'm happy as long as it's over 15 megabits/sec. (1,8MB/s)
The rule of thumb for 802.11 is that you can get TCP throughput of
50-60% of the signalling rate you're getting, and you only get the
best signaling rate under the best conditions.
So 50% - 60% of 54Mbps is 3,3MB/s - 4MB/s
Now for the (maybe) good news. Your Atheros AR9285 should be 802.11n capable. Your ASUS RT-N10U should also be a 802.11n router so if you connect with 802.11n the speed should be higher. (Your router goes up to 150Mbps, so not really the actual 11n standard but it might be a bit faster). But if your router is in 802.11-a/b/g/n mode it will connect much slower (somehow 11g and 11n don't mix well). If you don't have devices which need 802.11b or g, set the router to 802.11n only.
If you get a link-speed of just 64Mbps after doing this, switch back to 802.11g only because you'll only get an unstable connection this way (and you'll need to live with 3MB/s or buy new hardware). If you get a link-speed of 150Mbps you should see a much higher throughput.
What kind of wifi card do you have in your laptop? – Mike Pennington – 2014-01-07T11:35:09.467
1What is the "link-speed"? (It should give you the ("link"-)speed in your status-screen of the WiFi-connection) – Rik – 2014-01-07T11:39:27.733
Wi-Fi card: Atheros AR9285 (i have tried new drivers). Link-speed on status screen is 54 Mb/sec – ko4evneg – 2014-01-07T13:59:14.977
@ko4evneg: Have you tried using another Ethernet cable? You could use it to connect your laptop to the router and determine whether wireless is the problem. You could also use it to verify that the cable you currently have isn't faulty. – James P – 2014-01-07T14:00:31.357
I have connected laptop to the router with ethernet cable and tried to move file from PC to laptop. Speed was as it should be: ~12 MB/sec – ko4evneg – 2014-01-07T14:06:09.707
@ko4evneg: What make and model is the laptop? Try updating the wireless driver if possible. – James P – 2014-01-07T15:08:28.207
How are you transfering the files? I know my local wifi's FTP speed originally had a 3MB/s cap due to a setting in the client/server I was using. – root – 2014-01-07T15:26:21.443
Already tried to update drivers. I moving files using standard shares, so there is not any limitation here. – ko4evneg – 2014-01-07T20:19:42.877