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tano
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RB951G-2HnD - Unicast key exchange timeout

Thu Jan 05, 2017 5:03 pm

Hi,
I'm using a RB951G-2HnD device, i've configured it as a simple AP ( "Home AP" setting in the quickset page ) .

All my devices can connect correctly to the wireless SSID, but when two host ( a raspberrypi 1 and a alienware m11x laptop ) try to connect, i see on the mikrotik log "Unicast key exchange timeout" and the host fails to connect to the SSID network .
Thi issue appears on both the stable and RC firmwares, with the same error log .

The rPi is running openelec 7.0.3, the wifi module is realtek r8712u :
The Alienware laptop is running LinuxMint 18.1, and has a Broadcom Device 4353 (rev 01)(14e4:4353) 802.11a/b/g/n MIMO device .

I've seen that this issue is reported from many people, without a proper solution . http://forum.mikrotik.com/viewtopic.php?t=25820

Please let me know if you need further test \ logs .

Thanks
 
whitebox
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Re: RB951G-2HnD - Unicast key exchange timeout

Fri Jan 06, 2017 6:25 pm

However a user for four years now, this is my first posting. Maybe my info can help you Tano and I hope for the attention of "Mikrotik" for some substantial improvements in the near future.
In the past I had a "wired" house with UTP all over. Almost every appliance connected the hard way. I used OS 6.13 and later 6.23 without a major problem. My wireless devices were Windows laptops and smartphones. NASses , printer, IP-TV boxes, ATAs, desktops, media player en 4 Cisco switches completed the network. Worked all fine.
Now I have been living for 1 year in a rented house , so the ground floor and the upper floor are interconnected with WiFi. E.g. NAS upstairs and modem+router downstairs.
I started with a low cost modem/router/AP of the provider. This worked fine expect HD streams form my NAS to my media player were not flawless.
So I got my RB951G from the attic. This is when started a period in which I lost all my hairs.
The RB951 with OS 6.23 proved to maintain an unstable link with the ASUS WL-330N-3G - configured as a network adapter. All FTP and download sessions aborted after 30%-80% transferred. (never occured with the former modem/router/AP of my provider). Many sessions of all devices did often reconnect until HW-protection set to "CTS RTS"
I upgraded to OS 6.37.3 and 6.38 respectively but it got worse: a windows XP-Sp3 with Intel 2200BG client couldn´t connect anymore att all (Only on 801.11B). On G it connected "with limited access" but didn't receive DHCP-info. I switched between firmwares 2.x (don't remember) , 3.14 and 3.3. No luck.
I did some research on forums and decided to go back to OS 6.13. Now it works almost fine. Only 15% of FTP and download sessions aborted on my (internal) network.
Within 7 or 8 months I will have a "wired" house again, so I will count my blessings in the current situation. Goes without saying that after so many releases of OS this kind of problems still occur is quite unworthy of Mikroitik/Routerboard. Any ideas ?
Regards Hans
 
tano
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Re: RB951G-2HnD - Unicast key exchange timeout

Tue Jan 10, 2017 10:54 am

Hi,

Sorry but i didnt understand very well, did you have the same issue as described in my first post?
Did you find a way to solve it ?
 
R1CH
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Re: RB951G-2HnD - Unicast key exchange timeout

Tue Jan 10, 2017 8:26 pm

"Unicast key exchange timeout" is not a problem in itself, it's a symptom of a larger problem. The very first thing a wireless client does after connecting is to negotiate keys for security. This is what is timing out, giving the "Unicast key exchange timeout" message in your logs. As to why it's timing out, the answer varies. Most often, it's due to interference, preventing the station and AP from communicating properly. Try changing frequencies and use a 20 Mhz channel bandwidth. 2.4 GHz is a very crowded band, lots of non-WiFi devices also use it. Even just having eight nearby access points is enough to make a channel useless due to beacon spam. A spectral scan will show you more information about frequency usage. You should also make sure "adaptive noise immunity" is set to ap and client mode, this will allow the radio to tune internal parameters for best results. Keep in mind that wireless is a bi-directional system. While your router has a high quality radio and antenna, client devices may not - especially cheap embedded systems. So while the client may be able to transmit to the AP, the AP may not be able to transmit to the client.

If your devices support it, consider upgrading to a 5 GHz network. The signal has lower penetration and interference is less of a problem.
 
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pcunite
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Re: RB951G-2HnD - Unicast key exchange timeout

Thu Jan 12, 2017 6:06 am

"Unicast key exchange timeout" Most often, it's due to interference, preventing the station and AP from communicating properly.
...
If your devices support it, consider upgrading to a 5 GHz network. The signal has lower penetration and interference is less of a problem.
This was my experience too. The client had a wireless mic system that was only turned on for a few hours on Sundays and was bringing down the 2.4Ghz network. Running the spectral analyzer on the MikroTik help. Switching to 5Ghz solved the issue.

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