Couldn't achieve long range RH_RF95

[brandoncheah]

I'm working on a project using LoRa module Ra-01 Ai-thinker which is operating at 433 Mhz connected to an Arduino Nano.
i used the example codes in RH_RF95 to transmit and receive data between 2 nodes.
However i only can achieve a range of approx 30meters.
Anybody can help me out how can i achieve further range?
Tried adjusting the transmitting power still but still no improvement.

What I am doing is that:
-Sender will send "on/off" or "blink" to turn on/off or blink the receiver's LED

-Receiver receives data from sender and turns on/off or blink LED
-Then it sends back an acknowledgement back to the sender

Sender code
`
#include <SPI.h>
#include <RH_RF95.h>

#define RH_RF95_LONG_RANGE_MODE 0x80

typedef enum
{
Bw125Cr45Sf128 = 0, ///< Bw = 125 kHz, Cr = 4/5, Sf = 128chips/symbol, CRC on. Default medium range
Bw500Cr45Sf128, ///< Bw = 500 kHz, Cr = 4/5, Sf = 128chips/symbol, CRC on. Fast+short range
Bw31_25Cr48Sf512, ///< Bw = 31.25 kHz, Cr = 4/8, Sf = 512chips/symbol, CRC on. Slow+long range
Bw125Cr48Sf4096, ///< Bw = 125 kHz, Cr = 4/8, Sf = 4096chips/symbol, CRC on. Slow+long range
} ModemConfigChoice;

int lastButtonState1 = HIGH;
int lastButtonState2 = HIGH;
int buttonState1;
int buttonState2;
unsigned long lastDebounceTime1 = 0;
unsigned long lastDebounceTime2 = 0;
unsigned long debounceDelay = 20;
const int onoffbuttonpin = 4;
const int blinkbuttonpin = 5;
String data;
int redPin = 6;
int greenPin = 7;
int bluePin = 8;
int info;
int flag = 0;

// Singleton instance of the radio driver
RH_RF95 SX1278;

void setup() {
Serial.begin(9600);
while (!Serial) ;
if (!SX1278.init())
Serial.println("Notice:init failed");
SX1278.setFrequency(433.0);
SX1278.setTxPower(20);
bool setModemConfig(ModemConfigChoice Bw125Cr48Sf4096);

pinMode(onoffbuttonpin, INPUT_PULLUP);
pinMode(blinkbuttonpin, INPUT_PULLUP);

pinMode(redPin, OUTPUT);
pinMode(greenPin, OUTPUT);
pinMode(bluePin, OUTPUT);

digitalWrite(redPin, HIGH); // turn on RED during setup

}

void loop() {
uint8_t on[] = "on";
uint8_t off[] = "off";
int reading1 = digitalRead(onoffbuttonpin);
int reading2 = digitalRead(blinkbuttonpin);

if (reading1 != lastButtonState1) {

lastDebounceTime1 = millis();

}

if ((millis() - lastDebounceTime1) > debounceDelay) {

if (reading1 != buttonState1) {
  buttonState1 = reading1;

  if (buttonState1 == LOW) {
    SX1278.send(on, sizeof(on));
    Serial.println((char*)on);
    SX1278.waitPacketSent();
    digitalWrite(redPin, LOW);
    digitalWrite(greenPin, HIGH);
    flag = 1;    
  }
}

}
lastButtonState1 = reading1;

if (reading2 != lastButtonState2) {

lastDebounceTime2 = millis();

}

if ((millis() - lastDebounceTime2) > debounceDelay) {

if (reading2 != buttonState2) {
  buttonState2 = reading2;

  if (buttonState2 == LOW) {
SX1278.send(off, sizeof(off));
Serial.println((char*)off);
SX1278.waitPacketSent();
digitalWrite(redPin, LOW);
digitalWrite(greenPin, HIGH);    
flag = 1;
  }
}

}
lastButtonState2 = reading2;

if(flag = 1){
if (SX1278.available())
{
// Should be a message for us now
uint8_t buf[RH_RF95_MAX_MESSAGE_LEN];
uint8_t len = sizeof(buf);
if (SX1278.recv(buf, &len)){
String data = (char*)buf;
Serial.println(data);
Serial.println("RSSI");
Serial.println(SX1278.lastRssi(), DEC);

  if(data == "ack"){
     flag = 0;
     Serial.println("Received packet ack please wait 2 seconds");
     delay(500);
     digitalWrite(greenPin, LOW);
     digitalWrite(bluePin, HIGH);
     delay(1500);
     digitalWrite(bluePin, LOW);
     digitalWrite(redPin, HIGH);         
      }
    }
 } 

}
} //end loop
`

Receiver code
`
#include <SPI.h>
#include <RH_RF95.h>

#define RH_RF95_LONG_RANGE_MODE 0x80

typedef enum
{
Bw125Cr45Sf128 = 0, ///< Bw = 125 kHz, Cr = 4/5, Sf = 128chips/symbol, CRC on. Default medium range
Bw500Cr45Sf128, ///< Bw = 500 kHz, Cr = 4/5, Sf = 128chips/symbol, CRC on. Fast+short range
Bw31_25Cr48Sf512, ///< Bw = 31.25 kHz, Cr = 4/8, Sf = 512chips/symbol, CRC on. Slow+long range
Bw125Cr48Sf4096, ///< Bw = 125 kHz, Cr = 4/8, Sf = 4096chips/symbol, CRC on. Slow+long range
} ModemConfigChoice;
uint8_t ack[] = "ack";
RH_RF95 SX1278;

void setup() {
Serial.begin(9600);
while (!Serial) ; // Wait for serial port to be available
pinMode(3,OUTPUT);
digitalWrite(3,LOW);
if (!SX1278.init())
Serial.println("init failed");
SX1278.setFrequency(433.0);
SX1278.setTxPower(20);
bool setModemConfig(ModemConfigChoice Bw125Cr48Sf4096);

}

void loop() {
if (SX1278.available())
{
// Should be a message for us now
uint8_t buf[RH_RF95_MAX_MESSAGE_LEN];
uint8_t len = sizeof(buf);
int flag = 1;
if (SX1278.recv(buf, len))
{
Serial.println((char*)buf);
String data = (char*)buf;
if (data == "on"){
Serial.println("1");
Serial.println("RSSI");
Serial.println(SX1278.lastRssi(), DEC);

        if(digitalRead(3) == LOW){
        led_on();
        send_ack();             
       }
       
        else if(digitalRead(3) == HIGH){
        led_off();
        send_ack();            
        }  
       }      
       
    
     else if(data == "off"){
      Serial.println("2");
      Serial.println("RSSI"); 
        Serial.println(SX1278.lastRssi(), DEC);
      led_blink();
      send_ack(); 
  }
    else
    {
        Serial.println("Invalid");
        
    }

}
}
}

void led_on(){
digitalWrite(3, HIGH);
//delay(1000);
}

void led_off(){
digitalWrite(3, LOW);
//delay(1000);
}

void led_blink(){
for(int i = 0; i<5; i++){
digitalWrite(3, HIGH);
delay(100);
digitalWrite(3, LOW);
delay(100);
}
}

void send_ack(){
SX1278.send(ack, sizeof(ack));
Serial.println("sending ack");
Serial.println((char*)ack);
SX1278.waitPacketSent();
}
`