Implement logic to switch to a better WiFi connection

Oct 13, 2025 by talynt.org 144 views

DTU Connectivity Issue: Stuck in Bad WiFi Connection Despite Better Endpoint Availability

In this article, we will delve into a peculiar issue affecting the DTU (Data Transmission Unit) connectivity in a large area WiFi setup. The problem arises when the DTU decides to connect to a distant endpoint, despite a better and more stable connection being available. This issue has been reported by a user who has been experiencing data delivery dropouts with their onBattery setup. In this article, we will explore the possible causes of this issue, the expected behavior, and the necessary steps to reproduce the bug.

The user in question has a WiFi setup that spans a large area, with multiple access points available. However, the DTU sometimes decides to connect to the Fritzbox main router, which is the furthest away from it. This is despite the fact that the AX repeater, which is the closest access point, offers a rock-stable connection. The user has observed that this issue occurs when one of the repeaters restarts, there is a short power cut, or the Fritzbox runs an update and the Mesh is down briefly. In some cases, the DTU may simply decide to switch to the horrible connection.

The only way to fix this issue is to manually reboot the DTU via the web interface, if possible. However, this can be a challenging task, especially when the setup is located 300km away from the user. In such cases, the user has to call and instruct someone to power cycle the DTU. This is an inconvenient solution, and it highlights the need for some logic to ensure that the DTU switches to a better WiFi connection once available.

The expected behavior is that the DTU should automatically switch to a better WiFi connection once available. This means that if a more stable and faster connection is available, the DTU should use it instead of getting stuck with a horrible connection to a wrong endpoint.

Reproducing this bug may be challenging without a similar setup. However, the user has provided some information that can help in understanding the issue. The user has also mentioned that the issue has been occurring for a year, which suggests that it may be a persistent problem.

The user has installed the pre-compiled binary from GitHub releases. This suggests that the issue may be related to the installation method or the firmware variant.

The user has mentioned that they are using the latest version of OpenDTU-OnBattery. However, the issue has been occurring for a year, which suggests that it may be a persistent problem that has been present in previous versions.

The user has mentioned that they are using the generic_esp32s3_usb firmware variant. This suggests that the issue may be related to the firmware or the PIO environment.

Unfortunately, the user has not provided any relevant log or trace output that can help in understanding the issue.

In conclusion, the DTU connectivity issue is a persistent problem that affects the user's onBattery setup. The issue arises when the DTU decides to connect to a distant endpoint, despite a better and more stable connection being available. The user has reported that the issue occurs when one of the repeaters restarts, there is a short power cut, or the Fritzbox runs an update and the Mesh is down briefly. The only way to fix this issue is to manually reboot the DTU via the web interface, if possible. This highlights the need for some logic to ensure that the DTU switches to a better WiFi connection once available.

Based on the user's report, the following recommendations can be made:

Implement logic to switch to a better WiFi connection: The DTU should automatically switch to a better WiFi connection once available. This can be achieved by implementing some logic that checks for available connections and switches to the best one.
Improve the installation method: The installation method may be contributing to the issue. Improving the installation method can help in resolving the issue.
Update the firmware: Updating the firmware to the latest version may help in resolving the issue.
Provide relevant log or trace output: Providing relevant log or trace output can help in understanding the issue and resolving it.

By implementing these recommendations, the DTU connectivity issue can be resolved, and the user can enjoy a stable and fast connection.
DTU Connectivity Issue: Stuck in Bad WiFi Connection Despite Better Endpoint Availability - Q&A

In our previous article, we explored the DTU connectivity issue that affects the user's onBattery setup. The issue arises when the DTU decides to connect to a distant endpoint, despite a better and more stable connection being available. In this Q&A article, we will answer some of the most frequently asked questions related to this issue.

A: The DTU connectivity issue is a problem that affects the user's onBattery setup. The issue arises when the DTU decides to connect to a distant endpoint, despite a better and more stable connection being available.

A: The DTU connectivity issue can be caused by several factors, including:

One of the repeaters restarting
A short power cut
The Fritzbox running an update and the Mesh being down briefly
The DTU simply deciding to switch to the horrible connection

A: The only way to fix the DTU connectivity issue is to manually reboot the DTU via the web interface, if possible. However, this can be a challenging task, especially when the setup is located 300km away from the user. In such cases, the user has to call and instruct someone to power cycle the DTU.

A: The DTU gets stuck in a bad WiFi connection because it does not have the logic to switch to a better connection once available. This means that if a more stable and faster connection is available, the DTU will not use it and will instead get stuck with a horrible connection to a wrong endpoint.

A: Reproducing the DTU connectivity issue may be challenging without a similar setup. However, the user has provided some information that can help in understanding the issue. The user has also mentioned that the issue has been occurring for a year, which suggests that it may be a persistent problem.

A: The expected behavior of the DTU is that it should automatically switch to a better WiFi connection once available. This means that if a more stable and faster connection is available, the DTU should use it instead of getting stuck with a horrible connection to a wrong endpoint.

A: Yes, you can install a different firmware variant to resolve the issue. However, it is recommended to update the firmware to the latest version to ensure that you have the latest features and bug fixes.

A: The PIO environment is relevant in resolving the issue because it can affect the performance and stability of the DTU. Updating the PIO environment to the latest version can help in resolving the issue.

A: Yes, you can provide relevant log or trace output to help in resolving the issue. This can help the developers to understand the issue and provide a solution.

In conclusion, the DTU connectivity issue is a persistent problem that affects the user's onBattery setup. The issue arises when the DTU decides to connect to a distant endpoint, despite a better and more stable connection being available. By understanding the causes of the issue and the expected behavior of the DTU, we can work towards resolving the issue and providing a stable and fast connection.