Photon sending data only -- not listening (or hearing) - AP Problem

I make a product that includes a photon. The product is sold to our customers so I need some help without being able to do much myself in terms of adjustments or investigations into router settings, etc.

The issue:

The photon is able to wake up (device is battery powered and uses deep sleep) send reading, but the photon gets NO confirmation from server that a reading was sent. Furthermore, OTA updates fail. RSSI is reasonable at -65.

Attempted resolution:

Assuming it was an issue with the photon, I replaced the device containing the photon, but the new device behaves in the same way. Therefore I am assuming this to be a network configuration issue.

I have a two customer sites that seem to be affected by this issue. I have asked customers about routers and strange configuration settings. They claim to use a stock airport extreme. Any theories or experiences are very appreciated!

You might want to ask your customers to rename the 5GHz band SSID to something other than the 2.4GHz band's SSID. There has been a problem with some Apple and other routers that they try to steer traffic to the high band to improve performance but Photon's can do it.

Worth a try?