[German]A little story from the campfire as a Sunday sermon that caught my attention this week. One user had a problem with repeated packet loss on his WiFi connection. He set out to investigate and stumbled upon an incredible story. No, it wasn't the cat that had chewed through the cables.
I think just about every user of a Wi-Fi connection can tell stories about the signal dropping out from time to time or something else going wrong. As I was going through the posts on X this week, the following tweet caught my eye.
Luke Stephens wrote that he had just solved the strangest technical problem he had ever encountered.
WiFi connection loses packets
The problem: His notebook's WiFi connection was constantly losing packets. The screenshot in the tweet above shows a ping test that confirms the packet loss due to timeouts. The image: Packets are lost, then the WiFi connection works. After a while, the WiFi connection stopped working altogether and all packets were lost. When the user turned the WiFi off and on again, the WiFi connection worked normally again.
Searching for the root cause
As is usual in such cases, the person affected suspected a problem with his router, the cables, or his internet provider. So the usual troubleshooting measures were carried out: checking settings, replacing cables, switching the device off and on again, etc. Nothing worked.
It only happens in the office…
Finally, the person affected noticed that the problem only occurred when he was sitting in his office. The realization came when the man was participating in a video conference. There were repeated dropouts in the sound, so that he could hardly understand his conversation partner.
Moving the notebook to another room
As an immediate measure, the person affected unplugged the notebook from the monitor and keyboard. He wanted to try moving to another room in the hope that the connection would be more stable closer to the router. He noticed that the conference video immediately worked perfectly.
The idea that he was a few steps closer to the router in the new location and that this solved the problem did not really make sense to the person affected. This was because the router had always worked perfectly from the old location—until the packet loss suddenly occurred.
Think carefully: What did I change recently?
The man sat down at this point and began to think hard about what he might have changed recently at his workplace that could have caused the sudden WiFi problems. Loose cables, cleaned windows, or washed curtains could be ruled out.
Then he asked himself what he had recently changed in his desk configuration. The only thing left was that he had recently switched from a USB-C <-> DP cable for his external monitor to an HDMI <-> HDMI cable on his notebook.
Testing with the external monitor revealed the root cause
The man therefore reconnected the external monitor via the HDMI cable to his notebook. It was immediately apparent that packet loss was occurring again on the notebook. He disconnected the HDMI plug from the notebook, and the packet loss disappeared.
At the end of the day, it turned out that the cause of the packet loss was an insufficiently shielded HDMI cable. This interfered with the notebook's own Wi-Fi signal with high-frequency interference.
As a simple remedy, the man unrolled the HDMI cable that was behind his notebook. He then laid most of the HDMI cable behind his desk. This was enough to reduce the radio interference to such an extent that the Wi-Fi connection and thus the Internet connection now works perfectly. Finally, the person affected asked whether this was a fairly common problem?
