Uart data scrabbled


I connected an MCU to wizfi250 via UART and I communicate with an android device. When I send data from the android device to the MCU, then the MCU receives OK the data. Then it prints the incoming data to a screen and replies them back. The problem is that sometimes the replied data are not received as expected to the android device. For example: I send from android to MCU “helloWorld” the MCU receives the whole data , prints on screen “helloWorld” but when it replies back to wizfi and then to android, the then android receives “…lloWorld” or sometimes “he…oo.rld”, in general this is the pattern. I do not know but maybe the dots represents as no data?
Do you have any idea why the replied data are not as expected? I tried with different baud rates, 115220, 9600, 4800 , I cannot use 2400 or less because I have trouble communicating with a PC through a USB cable and putty in order to make the necessary configuration to wizfi.

I have noticed that if I send the data bytes from MCU to android with a small delay for each byte sent ,then the dots in the received data are more frequent but even still without delay the dots appears.
Is the wizfi and android not communicating at the same wifi speed?
Do you have any idea?

Thank you ,

Best Regards,

Andreas Achilleos