Stop interference w/ Xbee 802.15.4 Pro in RF rich environments?

I have several XBee 802.15.4 S1’s (w/ 10ec firmware) in the field that are experiencing connection failures. I can have two Xbee’s w/line of sight, and they loose connection in 20 ft. When I get the same pair back to my shop, They work up to 60 ft without line of sight. This leads me to believe there are rf interferance issues that I am not seeing.

These have been working fine for 3 years, and suddenly I am seeing a rash of these connection failures in metropolitan areas, NYC, and LA; and most of them have very dense wifi and audio streaming traffic.

I can not replicate these failures in my shop, nor can I go to where they are installed to do a energy scan.

Can anyone direct me to any literature or a set of guidelines I can follow to mitigate rf interfernce on products sold worldwide without having the ability to change parameters after they are sold?

The only perfect solution is to perform Energy scan and then select operational channel based on scan result.

If you cannot do this then I think you should set “CH” close to highest value. Lower channels in XBee face more interference from WiFi in my personal opinion. Therefore, although its not the perfect solution but it should still improve your current situation.