After a while i can give you some information about the hardware and status of the project:
I had to switch the linear voltage regulator to a low dropout counterpart with the same pinout so i chose the Microchip MCP1825S 3,3 v wich was the only one i´ve found with this pinout so i ordered them which took a while to arrive but now i am able to use the wifi access and everything is working as it should. The Problem was the increased power consumption which lead to a massive voltage drop and this low voltage triggered the so called "brownout detection" which is a safety function which constantly checks the voltage from the power supply and as soon as it drops very low it deactivates the MC beacuse it cant work or at least unreliable anymore.
My next target is to use NTP or a similar service substract the delay caused by the waiting time for the response which is by the way around 2-3 secs and implement some touch buttons and maybe make it possible to set a timer or an alarm via Bluetooth with my phone.
And i made a major mistake with the display PCB because i swiched SCL and SDA by mistake. Furthermore i want to make a PCB without all my errors and without the huge module for the DS3231 so more convenient to solder and use.
As soon as i know that everything works ill publish all PBC with a nice long CC license so you can order them by yourself and build what you want.
I also use a 5v step-down mode module from Pololu. Its a 1A one which is way to much and extremely expensive (nearly 8€) so you should rather use a 300mA- 500mA. You can`t input 12V directly to the LVR at least not in this one, 6V was the maximum. I tried it by accident and it worked for a short period of time but got like 45°C or similar (had no thermometer layin around) and after some time nothing worked because ive sucessfully grilled my LVR :D luckily i ordered 5 pcs so i just replaced it with a new one.
Now i have to rearrange the code a bit so i can use the module and NTP time maybe even implement the european equivalent to the daylight saving (BTW the EU has currently a online poll where you can vote for keeping this system or abolish it)
Ill try to work more on the code but this is my first project which is bigger than using an LED or mosfet or simple stuff like that :/
But any ´way ill upload code and everything with it once i know ive erased all the mistakes and some parts work properly.