I tested with a separate RTC module and STM32 board as well but without any luck.
It turned out to be, possibly, a software issue.
I rolled back to a previous version of the Arduino and STM32 programming platform and it worked just fine!
Now I am able to send commands and receive from the serial port as well.
Now the wifi connectivity needs to be fixed, but for this, I'll need the WeMos mini module since right now I have the WeMos mini lite.
Thank you all again for your help and support