/diy/ - Do It Yourself

Hello, ohm, I tried to mod my wi-fi for longer range, but I failed. I bought a 2.4 GHz 8dBi antenna, and some SMA plugs with cable attached. I then desoldered both original antennas, so the range decreased drastically (I was surprised that it worked at all). Then I soldered the cable to one of those circular things (pic related), and there was no improvement at all, compared to no antennas.
What I'd like to know is if this is caused by the cable being too long (2.5 m), or is my antenna faulty (when I check the resistance, it says it's infinite, but I saw many antennas where the shielding is shorted to the cable)? I checked for obvious things like broken cable. Also I think I did the soldering properly (shielding to the circular thing, cable to the middle).