We had a heatwave this week in Sydney. The temperature made it up to 45 degrees C. I had most of the farm off but left the Raspberry Pi running seeing as it doesn't generate much heat and takes a long time to process work.
I also spent a bit of time with the Raspberry Pi trying to work out why the network connection seems to disappear. I think it was caused by a combination of things. I tried different network cables. Nope not that. I tried a different (non-green) switch. No not that either.
I noticed it was using an IPv6 address and while my router supports it all the other machines have IPv6 disabled. To test it I plugged the old router in as it only does IPv4 and suddenly the network seems more stable but still drops out from time to time. I unplugged the powered USB hub and plugged the keyboard and mouse in directly and that seemed to fix that.
Seeing as I couldn't stay running the old router I then went looking for a way to disable IPv6 on the Pi. There is a file /etc/protocols that one can edit, so I commented out anything that mentioned IPv6. Then I plugged the current router back in to test it. All good.
To find out what address your Pi is using at a command prompt type: ip -d addr
To quickly test the network connection I just did: ping google.com
Just to make sure I also put the SD card into the older revision 1 model B and it too stayed working, so it looks like there is nothing wrong with it after all.
I still need to work out why IPv6 doesn't work on my network seeing as the router supposedly supports it, but it isn't urgent as my proxy server software is rather old and doesn't do IPv6 anyway - something else I need to look at updating.