I am doing multi connection on the BL652 as GATT client, but I am seeing data lost, what can I do to improve?

Answer

When you call "BleGattcOpen" before making those BLE connections, it will create a buffer to hold the GATT Server table, and the notification and indication coming from the GATT server. By increasing the size, you should see some improvement. But you must increase it as you need, or the module might run out of memory.