Previous situation:
1 rb433A AP running 5.8 and 10Mhz 'a' channel and legacy rates set to 'configured' at 18 and 36Mbps (so real rates are half of that)

3 clients; 1xrb133C3, 2x rb711-5Hn all running 5.8 and rates set to default.
On of the client has marginal singnals for NV2 (-81/-79 rx/tx) so decided to upgrade to 5.9 to see if the success stories told are true..

After upgrade of all clients the average signals improved about 3dBm. So almost double the signal!
Very good. Marginal links become good links!
CCQ all improved into close to 100% but probably because better signals.

I decided now to set rate settings to 'advanced' on both client first, and later also the AP. No problems, no visible changes.
Then I decided to set AP to default rates instead of configured; All clients dissassociated!
Went back to configured rates with only 18 and 36Mbps and clients came back. Double checked, client are all on 'default rate settings'

Decided now to upgrade AP to 5.9; no further increase in signals. No visible changes on the links.
Tried to switch back AP rates to ' default' (both in legacy as in advanced mode) and lost all clients.

Decided to set the AP back to configured rates and clients came back (works on both legacy and advanced mode)
Decided to switch the 6Mb rate on for both supported as basic rates and lost all clients again......

Tried with one client in 20Mhz channel. Same effect, default rate setting in AP not working. In configured rates (AP) clients connects only if 6Mbps is not chosen!

I am preparing a supout.rif to send to MT.

what supported/basic rates you have specified on the AP and station.
Enable the wireless,debug logs and check what does it say when you try to connect.
Send both AP and Station support output files when they can't connect to support@mikrotik.com

http://wiki.mikrotik.com/wiki/Manual:In ... -rates-a/g says:
"Client will connect to AP only if it supports all basic rates announced by the AP"

You're sure your clients have all needed basic rates set?

http://wiki.mikrotik.com/wiki/Manual:In ... -rates-a/g says:
"Client will connect to AP only if it supports all basic rates announced by the AP"

You're sure your clients have all needed basic rates set?

Yes, forgot to tell that. I tried several related settings on the client as well before I make this post. I am not a newbee as you know...

On the client in either 'default' setting or manual with the 6Mb supported and basic rates only, or with all rates supported and basic enabled or just the lower 3 rates on both supported and basic. The moment I set the AP to either default or use the 6Mb in both supported and basic all three clients disconnect.

It looks like clients in 5.9 don't like the use of 6Mb rate any more. (in both 10 and 20Mhz bandwith same result)

what supported/basic rates you have specified on the AP and station.
Enable the wireless,debug logs and check what does it say when you try to connect.
Send both AP and Station support output files when they can't connect to support@mikrotik.com

I made a more extensive report to you guys, it is given ticket #2011113066000691

But in short, I tried both 'default' on both end, which always should work.
Then I set manual rates in the client. As soon as the 6Mb becomes part of the setting and the AP is set to use either default (which normally means 6Mb basic and supported included) or manual with the 6Mb in it the client disconnects. (Setting the 6Mb rate in the client only would drop it anyway if that speed is not supported by the AP. On the other hand, if client is set to any other higher basic and supported rate that is supported by the AP it works...)

The only extra info I can give here (forgot to mention in the support request mail) is that the units previously have been working in 5.7 and 5.8 for weeks with on both AP and client only 18 and 36Mbps set a configured rates in the 10Mhz wide band.

Since most of my AP-client networks are back to 'default' rate settings again after the implementation of the 'advanced' rate setting option I am reluctant to upgrade these clients because if the issue is a real but it would mean my whole network goes down....

So, can anybody tell me that his AP-client network works fine in v5.9 where both AP and client have the connection rates set to default?

So, can anybody tell me that his AP-client network works fine in v5.9 where both AP and client have the connection rates set to default?

Well, not 5.8 but 2.4. Despite different band, 10MHz channel as well. Not "A" mode but "Only G" mode.

AP: R52Hn x RB433

preamble-mode=both proprietary-extensions=post-2.9.25 radio-name=\
AP-2400M rate-selection=legacy rate-set=default scan-list=default \

CPE: R52nM x X86 (PC Engines WRAP)

preamble-mode=both proprietary-extensions=post-2.9.25 radio-name=\
CLI-2400M rate-selection=legacy rate-set=default scan-list=2412 \
security-profile=MAF ssid=WISP-3G-MAF station-bridge-clone-mac=\

I tried this with safe mode enabled at client side anyway. Connected normally and 27/27Mbps @ CCQ > 95 both sides (with traffic).

Regards

Found the issue!

The AP has an ubiquity SR71-15 a/n card. It has both chains enabled but working in legacy 'a' mode.
Two sector antenna's connected.
Power setting was 27dBm which gave 27dBm per chain and 30dBm in total (for 6Mb rate only).
When power was set to 24dBm it gave 24dBm per chain and 27dBm in total (for 6Mb rate) and clients all came back even with 6dBm rate set.

After some more test found that I could set the card up to 26dBm per chain. But actually the recorded signals at the clients, special the distant one, actually started to become worse when powers above 24dBm where set in AP.
But all power settings up to 26 per chain worked for the clients. When 27dBm per chain is set clients disconnect.

I also noticed that during the test from 23dBm up to 27dBm per chain basically only the 6dBm rate saw its power levels change. All other rates stayed the same at 19dBm or less per chain.

Becuase card is sold as 27dBm and I could use every little bit of extra power to give a remote client some better signal (is in -76 to -81 region, marginal) I must have set it to 27dBm per chain which for a reason is not working on 6dBm rate.
The card is now set to 24dBm per channel and it actually give a 2dBm better signal at that distant client compared to 25, 26 ir 27dBm setting of that card.
Since 25-27dBm actually only see the power on the 6Mb channel increase it looks like they are than not used (as we saw, in 27dBm clients even don't connect). So the next rate is used which already give much less power.

Anyway, issue is sorted and all is working now. Reported this to support as well.