Hello,
I'm trying to improve the wifi range (YUN REV 2 firmware up to date), but when connecting an external antenna to the u-fl connector (tried two differents ones : 1dbi and 7 dbi), there is absolutely no impact in the yun wifi AP range (the signal strenght is absolutely the same).
Is this connector really usable or not connected ?
Regards,
Ed
Same problem,
I've seen in many posts that the connector for the external antenna looks like u.fl but is an SWF female connector, I suppose this was true maybe for the first YUN.
I have a YUN rev 2 like you and the connector seems actually identical to all the mini PCIe chipsets that I have...anyway, no change attaching external antennas 
I'm waiting for an answer to your question too.
Have you found anything?
I am facing the same problem. Plugging external antena does not have any
impact on Wifi signal strength.
I tested also external antena on Seeeduio Cloud and it work perfectly.
Is there any solution. I really like new Yun and I do not want to migrate to Seeeduion.
Best regards,
bop
On the YUN rev 2 the connector for external antenna does not appear to be connected on the circuit board. There is a 0 ohm jumper near the connector that goes to the onboard antenna. In order to use the external antenna, you need to remove the jumper to the onboard one and solder the connection to the U.FL connector.