【Typical Case】Troubleshooting SSID Detection Failures for Legacy NICs Following Ruijie AP W3B1 Upgade

Keywords:

Windows7, IEEE 802.11n, SSID Detection Failure
Issue Description

After an AP is upgraded from the old version (W1B4) to RGOS11.9(6)W3B1, Windows 7 devices using legacy NICs can no longer detect the SSID broadcast by the AP. However, other PCs and mobile phones can detect and connect to the SSID.
Involved NICs:
RealtekRTL8723AE
RealtekRTL8723BE
2. Device Model and Firmware

Device Type	Device Model	Firmware Version
Ruijie  wireless	AP820-L  V2	RGOS11.9(6)W3B1

3. Cause Analysis
The NICs on Windows 7devices cannot parse the A-MSDU field in the new firmware version, which prevents them from recognizing beacon frames with Extended Capabilities(including the MSDU field) that exceed 8 bytes.
The left figure shows an A-MSDU value of 0 in the W1B4 version, while the right figure shows an A-MSDU value of 3 in the W3B1 version.

4.
Solution

Change the amsdu-depth value to 0.

• If the AP works in Fit mode, run the following commands on the AC:
  

ap-config xxx---xxx is all or the AP's name
amsdu-depth 0 radio

end

wr

• If the AP works in Fat or Cloud mode, run thefollowing commands on the AP:
  

int dot 1/0

amsdu-depth 0

Int dot 2/0

amsdu-depth 0

end

wr