High Rx CRC Error and TCP transmission on Extreme AP 7662

[sungpill_han]

I have 7662 Extreme AP, firmware is 5.9.1.4-004R.
There are 3 PDAs(Zebra MC9200 scanning handgun) associated with it and they often have trouble sending data to web server. There's no pattern, but when I run netlog on the PDAs and the server, there are lots of TCP retransmission, duplicate, out-of-order. And the PDA eventually cuts the communications.

This started a month ago, but it seems it's getting worse. And when I tested with my laptop connecting to the AP, it shows the same symptom, so I guess the AP.

One thing I noticed in the AP is there are many RX CRC Errors and packet drop. The CRC error rate on RX side is almost 15%.

This is what I have done so far;

1. changed cable from AP to switch
2. show log in switch, nothing found
3. changed with the same model of AP, nothing improved, still CRC errors
4. current major settings of the AP

2.4 Ghz, Channel 11 fixed. No Smart.
No 5 Ghz, turned off
Power: 18dBm fixed. No Smart (I did this as it shows the error gets less).
Changed antenna from horizontal to vertical (MP-2499-HPA8-01-D

Last thing I may try is to upgrade firmware from 5.9.1.4-004R to 5.9.0-007R.

Any comment is appreciated.
Thank you.

[Winald_Oonk]

Looks like you have a interer on the 2.4 GHz.

This will interrupt your IP communication.

Try to use the 5GHz band.

You will need to setup the MC92N0 to support the correct channels for outdoor use.