Intel 6230 problems at high speeds with D-Link DIR-685

Some weeks ago I replaced an Atheros card with the Intel 6230 card in my Asus G73JH. 6230 was easier to get locally than 6200 and 6300 was not working at all (got error message device cannot start).
Initially I had some difficulties with plugging the antennas in, they provided bad signal and I had to play little bit with the antennas plugs to let them hold on 6230 card as they were kind of tired by previous failing experiments with the 6300 card. I got the connectivity working and the card was able to connect to my router DIR-685 at reasonable speeds.

After while I realized that sometimes I loose the real connectivity, but the wireless network connection status shows good signal, packets flying up and down and speed 162, 216, 243, up to 270 Mbps . Web pages don't load, ping even to the router doesn't work or tracert is visible to be loosing many packets. After some time the connection starts to work and usually its fine when speeds are bellow 135 Mbps. Sometimes it works fine even at speeds over 162 Mbps.

The drivers I installed are 14.3.0.6 - just basic without Intel Pro Set managing program. I haven't noticed any bluetooth problems when connecting my phone. Card was bought through some large local HW supplier and seems to be OEM.
DIR-685 has the latest firmware 2.01. In the area where I use my notebook the 6230 card can see up to 20 different wifi networks (the Atheros card saw ~12 of them, no 5.2MHz obviously). My network config is invisible SSID with WPA2 / AES security. Other computers are fine with this WLAN, over the weekend I may try connectivity in a different WLAN. I anticipate the source of the problem is the 6230 card and not the router.

What can I do to find the root cause of the problem (I want also to eliminate/minimize number of swapping attempts to keep the antennas' sockets at least in their current status)?

 

Can you disable BT while leaving Wi-Fi on?
There are known issues with limited throughput (to the point where there's basically no throughput at all) with this very card. These are caused by BT and Wi-Fi sharing the same frequency and antennas.

 

I switched BT off. Anyway I connect my phone for updates on very seldom basis - in fact I don't need it on all the time.

I'll keep testing for a while and see if it helped.

 

After few hours it seems I haven't experienced any connectivity problems, while before they occurred in about an hour already. It seems the BT-off solved my difficulties.

Thanks for advice
rep +1

 

My girlfriend has bought recently a Samsung NP530U3B-A01. This ultrabook is equipped from factory with Intel 6230 card. She hasn't experienced any problems with the WLAN connections, but I had issues again regularly when speeds went beyond 150 Mbps. In other than our home WLAN the speeds were always slower and I had no difficulties.
I found out the main difference between our cards setup was in Advanced Option:
802.11n Channel Width for band 2.4
Mine had Auto while hers had 20 Mhz Only. When I changed mine to 20 Mhz Only too the connection speeds dropped to about half - they became same as on her notebook. And connection became stable so far. I may try to switch hers to Auto and do other tests. May be one of the antennas in my notebook is not working well.

 

It's not a problem with an anttena but with overcrowded 2.4GHz band.
When channel width is set to Auto the router attempts to connect using 40MHz channels (that's why the connection speed is twice what it is with 20MHz channel)
In short 40MHz means you're using two channels at once and unless your live in the desert you're bound to have your channel overlapping with someone else's Wi-Fi. In most cases it's not a problem but in some cases- yours may be one of them- that means that some data doesn't actually reach you (router tries to re-transmit but that may make things slow).

Anyway- unless you need high throughput on Wi-Fi (you transfer lots of files over LAN) leave the channel at 20MHz.