In Consistence BLE Connection time on different devices.

[maliksaif]

The first connection on every time is in between 1 - 3 seconds.
The second connection times are a follows
Pixel 3 time is unchanged although sometimes it does not show my BLE Devices.
Nexus 6 First connection time 1 - 3 seconds , 2nd Connection time over 1 minute.
Samsung s20 5G First connection time 1 - 3 seconds . same as above.

The BLE Device which i am using is not from Nordic although it used UART Protocol.
I have tested the UART protocol communication from my Android App to Device it works great but the irregular connection time is one of the big problem i am facing

Let me know if you guys need any more information.

Thanks.