I think to change my common pigtail cable against one with a RG-316 cable with a length of 15cm between up-converter and ("8W") WiFi booster. I thought RG-316 has less loss. Now I have calculated the dB losses between RG-174 and RG-316 on https://www.timesmicrowave.com/Calculator . The losses are the same for this short length. Any comment is very appreciated.