Improvement of communication distance

Issue:LoRa range not enough

Setup:RAK831 as gateway, RAK811 as lora nodes and RAK firmware used for gateway


Details: I used above setup for small pilot project but most of node are out of range from gateway. What should I done to improve the range?
Also I want to know is there any most suitable configuration to improve communication distance of node by changing data rate with output power.
If we used high gain antenna for gateway, will it can improve the communication distance of LoRa

Place the antennas higher up in clear view of each other, and use a slower spreading factor.

Antennas with gain are problematic for LoRaWan gateways which need to cover nodes in a variety of directions. Gain in the sense of sending the energy in the horizontal plane is fine, but otherwise gain comes at the expense of better covering some directions than others.