This chapter summarizes everything related to the configuration, setup, and optimization of the Wi-Fi.

Basics

The first steps with the CTC modules and their Wi-Fi are often a greater challenge. That’s why we’re starting with a few basics here.

CTC essentially uses the standard functionalities of Wi-Fi. The term Wi-Fi is only used in German and is too general - the standard used is called “WiFi”. Our CTC router is also a regular Fritz!Box on which we carry out a few steps of the setup for you (see below section “Router Configuration”).

A regular Wi-Fi always has a name (SSID) and should have encryption (password) so that not everyone can enter unhindered. The encryption uses the standards WPA, WPA2, and WPA3.

  • WPA is largely ineffective as it can be cracked with little effort and freely available tools.
  • WPA2 can also be cracked, but with significantly more effort. For most devices (including the CTC modules), this is the maximum level of security that is supported.
  • If only WPA3 is activated, the CTC module cannot connect to the Wi-Fi.
  • You should therefore set your model railway Wi-Fi to “WPA2” or “WPA2 + WPA3”.

In addition to the non-unique SSID, there is also a MAC address of the Wi-Fi. This is unique worldwide but is usually used only at a technical level and often not shown to the user at all.

A Wi-Fi Access Point is a device that provides access to a network via radio (Wi-Fi) and does not offer any further network functionalities. A Wi-Fi router, on the other hand, contains the full range of a network center and typically also enables access to the Internet. For CTC it is important that the Wi-Fi router assigns the relevant IP addresses for communication using the DHCP function. The smallest version of a Wi-Fi router is the hotspot of a mobile phone.

There can be any number of Wi-Fi networks with the same SSID. This is used, for example, with a so-called Mesh to make the Wi-Fi available for a larger area using several Wi-Fi access points (and a Wi-Fi router). However, all these Wi-Fi access points must be connected to the associated Wi-Fi router. These Wi-Fi access points are also called “Wi-Fi Repeaters”. If the CTC module sees several Wi-Fi networks with the same SSID, it is difficult to predict which one it will connect to.

A CTC module knows two operating modes for the Wi-Fi:

  • In the configuration mode, the CTC module sets up its own Wi-Fi, so it acts like a mini-router. In this mode, the module can do nothing else but receive the configurations, especially the SSID and password of the model railway Wi-Fi. The Wi-Fi of the CTC module has only an SSID, but no password, so it is unencrypted.
  • In normal operation, the CTC module knows an SSID and an associated password and tries to log into the Wi-Fi with this SSID at startup.

    Wi-Fi Icon

Since the reception quality of the Wi-Fi signal significantly influences CTC, it is displayed at various points with the following symbols:

Symbol Meaning
ctc-app-doku-icon Optimal Wi-Fi reception (> -67 dB)
ctc-app-doku-icon Good Wi-Fi reception (> -70 dB)
ctc-app-doku-icon Acceptable Wi-Fi reception (> -80 dB)
ctc-app-doku-icon Poor Wi-Fi reception (<= -80 dB)
ctc-app-doku-icon CTC module with old firmware that does not yet transfer signal strength.
ctc-app-doku-icon CTC module has not checked in for at least 3 seconds.
ctc-app-doku-icon CTC module has not checked in for over 10 seconds

The last two symbols (yellow and red) do not provide any information about the reception quality of the CTC module. It is entirely possible that the CTC module is still well connected to the Wi-Fi, and the CTC app has lost its connection to the Wi-Fi. This is especially likely when all CTC modules switch to yellow or red.

Router Configuration

In this section, we collect documents for configuring routers:

Both laptops and smartphones as well as tablets have an increasingly strong urge to connect to the Internet. This leads to them being reluctant to connect to Wi-Fi networks without internet access, and they also like to spontaneously leave these networks. CTC does not need Internet access, which is why the model railway Wi-Fi is often set up without Internet connection.

The trick is just to get the devices running the CTC app to connect to the model railway Wi-Fi and not to leave it spontaneously. Here are a few tips:

  • Connect PCs and laptops, which don’t need to be moved during model train operation, via network cable.
  • Turn off the “connect automatically” option for all Wi-Fi networks or select it only for the model railway Wi-Fi
  • Switch the smartphone to airplane mode and then only activate the Wi-Fi.
  • Check if there are any problems, whether the PC or mobile device is still connected to the correct Wi-Fi.

    Tips for optimizing Wi-Fi reception quality

  • Laptops or PCs, which are not moved, should be connected to the Wi-Fi router via LAN cable. Often, with reception problems, it has been shown that the cause was the laptop, not the CTC module.
  • Use 5 GHz Wi-Fi for the device where the CTC-App is installed. This forces a detour via the Wi-Fi router, which often has a significantly better position for communication with the CTC modules.
  • For smartphones/tablets, there are so-called Wi-Fi Analyzer apps, for example, for Android the ad-free “WiFi Analyzer (open-source)”. With these, you can move to different locations of your layout and check how good the reception of your model railway Wi-Fi is and how many competing Wi-Fi networks you have. It may be worth changing the channel of your model railway Wi-Fi.
  • With the help of the WiFi-Monitor, you can display the signal strength of locomotives more accurately and also over time. You can use the displayed graph to find the optimal position for your Wi-Fi router.