I have an issue where my pc will randomly disconnect from my network. It will be going along just fine then it will loose connection to the network (saying "No internet access"). When it is like this, I can't ping the router/gateway. I have just replaced my router with a new one, both were set to DHCP and standard settings to try to isolate the variables, but it still happens. I have updated the motherboard firmware, reinstalled the network drivers, and monitored the packets in wireshark, but nothing seems to show. It just runs fine then randomly disappears off the network. Note: It is a wired connection through a Ethernet-over-power transceiver.
How frequently does this occur? I've used the PowerLine network adapters before and have not had much luck with them (although that was quite a while ago, the technology has probably improved since then). When you lose network connectivity can you see if you still have link lights on your NIC? I suspect you won't.