Strange problem connecting on 5500 channel

RouterOS Wireless Networking
1

Hi,

I have three MT boxes with the same configuration RB411AH, ROS 4.5, R52N. One of them is configured as an AP and the rest as a station. The one client is approx 7km from AP the second one approx 4km. Nstreme (single way) is used and Country is set to Czech Republic
The problem: When the client scan range is set to 5180-5800 and the AP is using 5500 the clients will not connect. After the AP is set to any other channel higher then 5500 the clients will connect. If the AP is transmitting on 5500 and the clients scan range is set to 5500-5700 (the start of the range is important) the clients will connect.

The problem is visible in Scan mode too. When AP is set to 5500 the client doesn’t see the AP in Scan. After the Ap is tuned to 5505 the client see the AP in Scan.

–

It looks like the client is skipping the 5500 channel when 5180-5700 interval is used in Scan List. There are other observations which can lead to idea that the client is receiving the signal from AP on lower levels when the APs channel is close to 5500 (tried on 5515, 5510 and 5505 - the lower frequencies had lower dBm in Scan on client, the 5500 was not detected on AP). Like the client added some attenuation (or lower gain) on 5500.

Before we discovered the strange behavior of Scan List we thought there is a big interference on 5500, but there isn’t probably. And of course we have other of links working on 5500 with 5180-5700 scan list (but there may be differences in HW config).

2

Run

/interface wireless info print

and you will see the frequency, which are included into default scan-list (it depends on frequency-mode and country settings). Scan-list=default users frequencies from the info to search for access point.
Most likely 5500 frequency is not included there and you should add manually it to scan-list or keep frequency-mode/country settings the same on all nodes.

3

Thanks you for the answer!

There is an excerpt of the info print from one of the radios:
interface-type=Atheros AR5416
chip-info=“mac:0x80/0x2, phy:0xd0, a5:0xc0, a2:0x0, eeprom:0x0”
pci-info=“00:12.0” capabilities=tx-power-control,ack-timeout-control,
virtual-ap,alignment-mode,scanning,nstreme,
sniffing,power-channel,ht40-a,ht40-g,wmm,14
default-periodic-calibration=enabled
supported-bands=2ghz-b,5ghz,2ghz-g,5ghz-10mhz,5ghz-5mhz,2ghz-10mhz,2ghz-
5mhz,5ghz-11n,2ghz-11n
2ghz-b-channels=2412:0,2417:0,2422:0,2427:0,2432:0,2437:0,2442:0,2447:0,
2452:0,2457:0,2462:0,2467:0,2472:0
5ghz-channels=5180:0,5185:0,5190:0,5195:0,5200:0,5205:0,5210:0,5215:0,
5220:0,5225:0,5230:0,5235:0,5240:0,5245:0,5250:0,5255:0,
5260:0,5265:0,5270:0,5275:0,5280:0,5285:0,5290:0,5295:0,
5300:0,5305:0,5310:0,5315:0,5320:0,5500:0,5505:0,5510:0,
5515:0,5520:0,5525:0,5530:0,5535:0,5540:0,5545:0,5550:0,
5555:0,5560:0,5565:0,5570:0,5575:0,5580:0,5585:0,5590:0,
5595:0,5600:0,5605:0,5610:0,5615:0,5620:0,5625:0,5630:0,
5635:0,5640:0,5645:0,5650:0,5655:0,5660:0,5665:0,5670:0,
5675:0,5680:0,5685:0,5690:0,5695:0,5700:0,5735:0,5740:0,
5745:0,5750:0,5755:0,5760:0,5765:0,5770:0,5775:0,5780:0,
5785:0,5790:0,5795:0,5800:0,5805:0,5810:0,5815:0,5820:0,
5825:0,5830:0,5835:0,5840:0,5845:0,5850:0,5855:0,5860:0,
5865:0

The 5500 channel is present (and on there radios too)

Regards
D. Toman

4

If you set 5500 manually to scan-list at the client.
Does it work?

5

In the first message I described that if the scan-list starts with 5500 (5500-5700) the client connects to the AP. But maybe I didn’t understand the question… I didn’t try to use 5500 alone in scan-list.


Regards
D. Toman

6

When frequency is included to wireless info print, station router should check it, while it is selecting for AP.