We use Cisco1310 at our customer location; the units are installed in the outdoor for a distance of 4 KMS, with external antenna. The link is slow and the TTL on the Ethernet is not stable, the SSID and the WEP key is applied for 40 BIT encryption, tried different channels there were no improvements please suggest
You might want to verify your alignment. I would put both units in install mode and verify the signal levels you are getting.
The signal levels that you are seeing are not in percentage, but are the actual signal levels. Your SNR shows 9dB, and should be at least 20dB. You can see that your data is mostly going out at 1M. You need to improve your SNR.
Even if you had your power at 1mW, your distance for using parabolic dishes is 2.27Km. You must be at least 21 feet above all obstructions at 1mW.
Here is a document that shows what the RSSI lights should be when the unit is in install mode. Again, because of the nature of the parabolic dish, alignment is critical and should be on a very stable mast.