Above you mentioned being able to ping both a public and private IP for your RPi. Would I be correct in assuming that this means you’ve made the dump1090 web interface publicly available? This is why I ask this. Basically, dump1090 will abruptly die if a bad URL is requested.
When I built my box at home, I initially had the web interface publicly available as well, mostly cause it looked cool and I thought my friends and family might enjoy checking it out from time to time. But a couple days after getting it set up, it would stop feeding positions to FA and simultaneously the web interface would stop responding. Investigating via top/ps showed that dump1090 was dying in these cases. So I disabled the port forwarding that made the interface publicly available, and I have had no failures since then. (this was roughly a week ago)
There are also some possible security issues stemming from exposing the web interface. Overall, it’s not recommended to have the web interface open to the public. If I’m reading your comments correctly, then I’d advise that you disable public access and then see if your problems go away.