Every so often (few weeks?) my HA install on RPI 4 takes down my whole home network, like a local DDoS attack! Unplugging the Pi gets the network back but I have to hard power it off and on to get it working back on the network. Any wise pointers or ideas as to how I might diagnose this problem would be very much appreciated.
What OS are you using on it?
Do you have any log files that may indicate what’s going on? I would start by looking at the OS logs on the PI and maybe look for the logs on your router to see what all is going on.
I own a few of these devices and I do not have any issues with them.
This may be a useful read for you.
Thanks for the pointers people. Will see what I can discover…
for me i had the same kind of problem using HA in a VM of an old computer i notice that if i turned off mDNS repeater on my edgerouter it would resolve the problem. For me it was as soon as i turn on the VM it would saturate my network… not only part time.
i have wireshark it and discover Ha was sending all its traffic to the router’s internal 224.0.0.251 so i just made a firewall rule that any HA traffic that has a destination of 224.0.0.251 would be drop by the router (switch0/local).
i hope it help. and if you fine the source of that problem please let us know 
Thanks for your answer @sirius682. I think that may indeed be the problem I’m experiencing so I’ve taken your lead and created that rule on my router. mDNS Broadcast traffic seems to be the culprit and reading a few more threads around the Internet, I suspect its a buggy IoT device on my network broadcasting via HA.
I have the same problem. What kind of router do you have and what type of rule did you employ? Did it prevent network crashes?
I’ve a Ubiquity Edge Lite router. So far adding that rule to drop packets has worked. I haven’t had the network swamped since.
Yeah I’ll need to figure out how to do that with FreshTomato, if it’s possible at all.
An update on this snarly problem. As per my previous post. Adding the rule on the router to drop packets has worked in that my network doesn’t get swamped anymore when this event happens. Unfortunately though, I still lose the HA server every so often and have to physically drop power to the Raspberry Pi and re-power it. Any further ideas much appreciated!
I’m running in the same issue. Any news on this?
This instability problem with the Raspberry Pi 4 was a long standing issue of which many people worked on to resolve. The issue was identified and was resolved with an update to the Raspberry PI OS a month or so ago.
So if you are running the most recent version of HASS OS on your Pi 4 the problem will hopefully be no more.