D1 mini lite won't connect to WLAN - arduino

Question

I am building some simple IoT devices like tem / humi and window sensors for the house and would need some support with a simple method to connect a D1 mini lite to my WLAN.
There are already more than enough examples and tutorials out there to do this and I was already successful to connect a D1 mini and a Raspberry Zero with the sensors and to my WLAN and post some messages on a local MQTT server.
It was pretty clear and easy to do this and worked as I was told for the D1 mini and the Rasp Zero, but the D1 mini lite just won't connect to my WLAN. I kept the sketch (see code below) very simple and tried the exact same code for D1 mini and the D1 mini lite. The mini connects and the lite won't.
I am using the Arduino IDE and installed the additional board manager from here: http://arduino.esp8266.com/stable/package_esp8266com_index.json
For the D1 mini I chose "LOLIN(WEMOS) D1 R2 and mini" and for the D1 mini lite I chose "LOLIN(WEMOS) D1 mini Lite" under Tools->Board->ESP8266 Boards (3.0.2) (seems to be the most current one according to github)
The IDE gave me no errors on compiling or transferring to the board. The blue LED blinked on both boards when transferring the compiled sketch and when plugin in USB.
The serial monitor shows the IP of the connected WLAN for the D1 mini after 2 or so printed dots. The D1 mini lite keeps on printing dots without ever connecting or showing any other error / exception.
Is there a way to check the functionality of the wifi functionality of the board or to see why it was not able to connect? Any hint or link to documentation is appreciated.
I am not aware of having to use another other WiFi framework for the D1 mini lite as the one I used in the pretty much copy and pasted sketch. If this is the case would someone please let me know where this is mentioned to avoid future problems.
As I am very new to C++ - did I miss anything obvious? Please let me know and I will add the information or correct my beginners fault.
#include <ESP8266WiFi.h>
char ssid[] = "wlanssid";
char pass[] = "supersecretpassword";
void setup()
{
Serial.begin(115200);
Serial.println();
WiFi.begin(ssid, pass);
Serial.print("Connecting");
while (WiFi.status() != WL_CONNECTED)
{
delay(500);
Serial.print(".");
}
Serial.println();
Serial.print("Connected, IP address: ");
Serial.println(WiFi.localIP());
}
void loop() {}
My settings in Arduino under Tools for the mini lite