ASUS N550JK-DS71T - slow wifi download speed with N-router

I have a ASUS N550JK-DS71T laptop which has about half the download speed with wifi compared to a similar laptop (with a N-type wireless card) right next to it. So this issue is not due to ISP or router. Upload speed is fine.
I used speedtest.net and speakeasy.net.
Laptop has the INTEL AC 7260 wireless card with the latest driver on Asus website (V17.0.1.5).
I checked the power settings and they are on High Performance.
I have a N-router set to N.

My N-router is a D-Link DIR-615 (Hardware E1, Firmware Version : 5.00NA).
It has the latest firmware from 2009.
It is a single band type at 2.4 Ghz.
Here is a link to the manual:
ftp://ftp2.dlink.com/PRODUCTS/DIR-61...AL_5.20_EN.PDF
On page 117, the specs list the wireless speed which are up to 108 Mbps.

I set it to:
- Auto 20/40Mhz (the other option is 20 Mhz, which I also tried)
- 802.11n only
- Channel 6 (I tried Auto and other channels too)
- WAP2
- AES

Both laptops (the Asus and a Dell E6240) have the same Wireless card settings in Device Manager.
They both have the Wireless Mode option to 6. 802.11a/b/g.
The only difference is that the Dell card has an extra setting called '802.11n mode' which is Enabled.
The Asus has the Intel AC 7260 card and the Dell has the Intel Centrino(R) Advanced-N-6205 card.

So it seems that the Intel AC 7260 card is not working well with my N-router. Would there be any settings to change to make the AC card works better with a N-Router?
I am now also considering getting a better/newer N-Router or even a "low-end" AC router like the Belkin AC 1200 DB Wi-Fi Dual-Band AC+ Router at around $100.

Also could there be an issue related to the fact that the Asus laptop is running Windows 8.1 as opposed to the Dell which runs Windows 7?

 

You mentioned getting the driver from Asus' site. Have you tried a newer driver version from Intel's site?

Forewarning: A lot of users have complained about Intel drivers for this card, so this may take some playing around with.

 

The new cards may not play well with old routers, especially when DIR-615 used draft N protocol during that period.
Try a newer model, see how it plays out.

 

Thanks for your feedback.

I bought a Netgear AC1200 R6100 wireless router and this fixed the issue. I now get about 30 Mbps for download (upload has not changed and is still around 11 Mpbs as expected) anywhere in the house! This is quite good since my internet plan with Comcast gives me 25 Mpbs.
It is possible that the issue could have also been fixed with a newer N-router but I have not tried it.

Note that when the battery is getting lower (lower than 30-40%) and when the wifi is set to 'Maximum Power Saving', the wifi speeds are significantly reduced! Down to a few Mpbs! Once the setting is changed to 'Maximum Performance' or plugged in, the wifi speeds are back to normal. While I understand that the wifi speeds would be reduced under 'Maximum Power Saving', I do think that they should not be allowed to go down so low and inconsistent: it was really hard to browse the Internet (got the error in the browser of 'no connection').

By the way, I use the latest Intel AC 7260 driver: 17.0.6.

 

That's really good to know that the issue is resolved.
Regarding the wifi driver, there is a 17.1.0 but it is not liked by some users, see below.
Download