I use a Raspberry Pi 4B with Home Assistant to provide some Home Automation functions.

The Pi4 has an official POE HAT and connects directly to a POE Switch.

Over the last few months, I've had several outages not only of the Pi but of a security camera, WiFi Hotspot and other devices directly connected to the POE Hat.

Last month I found that whilst the switch was powering devices and lights were flickering indicating network connectivity, there was no network traffic. I decided at the time that it was the switch that had failed so swapped it for a new one.

Now again I've had the same problem. Troubleshooted by unplugging all the devices and then over the course of a few hours plugging them all back in again. On connecting the Pi with the POE HAT, the network connection dies.

I've now removed the POE HAT and have powered the Pi with a normal official power supply and all is well.

Is anyone aware of a failure mode with the POE HAT that would lead to the loss of network connectivity while still powering the Pi that also causes the loss of connectivity on all other devices connected to the same switch?

Electronic and Computer Engineer
Pi Interests: Home Automation, IOT, Python and Tkinter

Turn out it might not be the POE Hat itself but either the Pi or Home Assistant itself.

Any ideas what could cause a Pi to kill all network traffic on a POE Switch?

Electronic and Computer Engineer
Pi Interests: Home Automation, IOT, Python and Tkinter

A work colleague mentioned babbling nodes when I was mentioning this issue.

Does anyone have any strategies for identifying whether this is the case or not? I have perhaps forgotten my networking basics but I thought that switches were supposed to prevent babbling nodes from bringing down the rest of the network.

Electronic and Computer Engineer
Pi Interests: Home Automation, IOT, Python and Tkinter

I'm having the same exact issue. I have a feeling that its introducing some serious signal noise to the network. I've had the PoE hat for a while, finally had a project i need it for, and its repeatedly taking down everything on the PoE switch which is an enterprise grade Aruba PoE switch. Some UDP traffic still gets through, but TCP seems to fail completely.