S7 Edge or LG connecting is difficult

[zcmm]

 Hi,all
         my device：
              NRF51822
              S110
              SDK:8.1.0
              connect parameter as follow：
                     #define SLAVE_LATENCY                   0 
                     #define CONN_SUP_TIMEOUT                MSEC_TO_UNITS(4000, UNIT_10_MS)  
                    #define FIRST_CONN_PARAMS_UPDATE_DELAY  APP_TIMER_TICKS(5000, APP_TIMER_PRESCALER) 
                    #define NEXT_CONN_PARAMS_UPDATE_DELAY   APP_TIMER_TICKS(30000, APP_TIMER_PRESCALER)
                    #define MAX_CONN_PARAMS_UPDATE_COUNT    3  

                   #define MAX_CONN_INTERVAL               MSEC_TO_UNITS(40, UNIT_1_25_MS)
                   #define MIN_CONN_INTERVAL               MSEC_TO_UNITS(20, UNIT_1_25_MS)
       In only one bluetooth device environment（Only my device and Phone），
  i use galaxy S4 、Iphone6、Iphone5、Iphone 7、Huawei P8 ，it is very fast and stable

when these phone connnect with my device .

       But when i use these phone as follow,it is very difficult to connect with my device or Connection is not on my device completely.                                    
       Galaxy s7 Edge(Android6.0.1)  Galaxy s5(Android6.0.1)  Sumsung Galaxy J3(2016)(Android 5.1.1)  LG.

How should I solve this problem????

[Hung Bui]

Hi,

So for scanning there are 2 parameters decide how frequently a scanner scan. They are scan interval and scan window. Scan interval is how often the scanner do scanning and scan window is how long on each scan session the scanner stay in scanning mode.

If scan window is close to scan interval, it's a aggressive scanning, if scan window is only a small portion of scan interval, then it's kind of slow scanning. Aggressive scanning can give you more chan catch advertising packets make it faster to connect, but it will consume lots of power and drain the phone's battery. It's opposite for the slow scanning, it's harder to connect but it save power.

I assume on S7edge, and LG it's slow scanner.