I have an extensive home automation setup and multiple computer users at home - 100 nodes roughly.

Once every month or so the network grinds to a halt and I can't put my finger on it. It happened last night when the my switch (Unifi Dream Machine Pro) reported that it could no longer connect to the Internet (FIOS direct ethernet). I checked FIOS and it was running fine. I then unplugged both switches and the UDMP was happy. Then I started plugging the switches and the devices back in one by one until I find what I think is the cause. But invariably it will be something different each time and often I have issues for a few hours and the connection I thought was the issue might not be the one.
So in my limited network knowledge this tells me that some device is potentially jamming up the network but I can't seem to pinpoint it to a single device, in fact it may be more than one.
I downloaded PingPlotter as several sites said it can be used to find out what is slowing down your network.
Ideally I can get something that says this IP is doing something bad and warns me so I can track it and take any corrective measures before everything stops responding. Thanks.