Upload & Sell: Off
I tried my Eye-Fi Pro X2 in my 1DsIII and my iphone 4s....no problem with the iphone and EyeFI finding each other. Distance was about 15 feet, indoors. I made sure that my iphone was not connected to another network wireless signal, if it is, nearly impossible to dislodge the other signal with EyeFi signal.
No problem with the phone signal tied in......
If you really want to get some distance and not worry about it, go with CamRanger, it has a true WiFI signal and you can lock your iphone or ipad directly into the network and have it stick to it. They advertise up to 150 feet......
I have both and depending on what I want to do would dictate which device I would use....they are different and to me they have different purposes......
Cam ranger looks cool, quite a different price though.
By doing some tweaks in the settings I have managed to keep the network running instead of shutting down every time connection is lost. I still find it difficult to get more than half the distance you describe!
Could the card be a 'bad copy'? Haven't bought it yet, I can still return it to the owner and buy a new instead.