Creating a webserver on a Wemos D1 mini pro I am trying to put a web server on my Wemos D1 mini pro. I am using this example for the Arduino code: 
https://github.com/wemos/Arduino_D1/blob/master/doc/esp8266wifi/server-examples.rst


#include &lt;ESP8266WiFi.h&gt;

const char* ssid = "GL-AR300M-ceb";
const char* password = "********";

WiFiServer server(80);

void setup()
{
  Serial.begin(115200);
  Serial.println();

  Serial.printf("Connecting to %s ", ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print(".");
  }
  Serial.println(" connected");

  server.begin();
  Serial.printf("Web server started, open %s in a web browser\n", WiFi.localIP().toString().c_str());
}


// prepare a web page to be send to a client (web browser)
String prepareHtmlPage()
{
  String htmlPage =
     String("HTTP/1.1 200 OK\r\n") +
            "Content-Type: text/html\r\n" +
            "Connection: close\r\n" +  // the connection will be closed after completion of the response
            "Refresh: 5\r\n" +  // refresh the page automatically every 5 sec
            "\r\n" +
            "&lt;!DOCTYPE HTML&gt;" +
            "&lt;html&gt;" +
            "Analog input:  " + String(analogRead(A0)) +
            "&lt;/html&gt;" +
            "\r\n";
  return htmlPage;
}


void loop()
{
  WiFiClient client = server.available();
  // wait for a client (web browser) to connect
  if (client)
  {
    Serial.println("\n[Client connected]");
    while (client.connected())
    {
      // read line by line what the client (web browser) is requesting
      if (client.available())
      {
        String line = client.readStringUntil('\r');
        Serial.print(line);
        // wait for end of client's request, that is marked with an empty line
        if (line.length() == 1 &amp;&amp; line[0] == '\n')
        {
          client.println(prepareHtmlPage());
          break;
        }
      }
    }
    delay(1); // give the web browser time to receive the data

    // close the connection:
    client.stop();
    Serial.println("[Client disonnected]");
  }
}


It uploads fine and when I open the serial monitor get this:  

Connecting to GL-AR300M-ceb . connected
Web server started, open 192.168.8.119 in a web browser  

When I go to the IP address that it gives in the monitor, I only see a blank page. I also can't inspect element, so it doesn't load the HTML part I guess.
When I change the code like this:  

if (client.available())  
{  
//        String line = client.readStringUntil('\r');  
//        Serial.print(line);  
//        // wait for end of client's request, that is marked with an empty line  
//        if (line.length() == 1 &amp;&amp; line[0] == '\n')  
//        {  
//          client.println(prepareHtmlPage());  
//          break;  
//        }  
          client.println(prepareHtmlPage());  
      }  


then i see this
 

And when i add the break in the code like so:  

client.println(prepareHtmlPage());  
break;  


in the code, i get the blank page again.  

Does someone have an idea what the problem might be?
you should go for the "Advanced Webserver" example provided by the ESP8266 libraries in your Arduino IDE.
The webserver is using callbacks like

server.on ( "/", handleRoot );
server.on ( "/test.svg", drawGraph );


and so on. 
Then you can use these handles to give back a html page to your browser like

server.send(200, "text/plain", message);       //Response to the HTTP request


Note how the function returns an 200 http code to your browser, which is mandatory for showing up your web page!