Add network to Qt Project - c++

Question

I try to use the QtNetwork library and added all dependencies for it in the .pro file. But when I compile my code Qt Creator fails in building the project and claims
C1083: Include "QTcpSocket": No such file or directory - telnet.h:4
I thought adding network to the .pro file would be enough?
networkmonitor.pro
#-------------------------------------------------
#
# Project created by QtCreator 2017-07-24T13:18:19
#
#-------------------------------------------------
QT += core gui network charts
# greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = networkmonitor
TEMPLATE = app
# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS
# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0
SOURCES += \
main.cpp \
mainwindow.cpp \
telnet.cpp
HEADERS += \
mainwindow.h \
telnet.h
FORMS += \
mainwindow.ui
telnet.h
#ifndef TELNET_H
#define TELNET_H
#include <QTcpSocket>
#include <QTcpServer>
#include <QDebug>
class Telnet
{
public:
Telnet();
void sendValues(QString _ip, int _port, QString _message);
private:
QTcpSocket *socket;
};
#endif // TELNET_H

Answer 1

Normally this means you just forgot to re-run qmake