how to ensure connection of U. FL connector

I am getting severe range problems with my 3dbi antenna and I am using XBEE-PRO-S2B RF module. So I switched to 9dbi antenna assumming that the range will get enhanced. But I din’t receive any positive result, the problem is still same. Therefore, I checked the connection between the internal centre point and outer circumference of U.FL male connector which is soldered on Xbee module and it is showing short.
Then I checked the same with my SMA antenna which is female and it is showing open. Now I am not able to understand whether this kind of internal connection is proper or not and my assumption on this that I am getting range problem is due to this internal connections if they are not proper.
Kindly suggest on this and do the needful to explain the connection part.
Thank You
Best regards

How are you measuring the short? Between the Center conductor and what other component?

we checked by the multimeter between signal point and ground point of U.FL connector

Yes on the modules I have that work, I do show continuity between the Center conductor and the GND pad.

I am using the xbee module in boost mode with power level 4 and I am getting only 160m range(line of site) not even close to 1.2Km as mentioned in datasheet. Inspite of trying with different gain antennas(3dbi and 9dbi) the result is same. I also tried on building’s terraces after knowing about the fresnel zone. My device is battery operated(3V,5000mAh-CR26500E) and is working in pin hibernate mode which wakes up after a pre defined transmit interval for transmission and goes again to sleep.

Are you using a U.FL to SMA or U.FL to RPSMA cable to connect your antenna with?

I am using U.FL to SMA connector.
Yesterday we have check range on Straight road & we achieve range upto 500 meters.

What is the full part number of the module you are working with? How high up were both antennas above ALL obstructions?