Recently I’ve had alot of unexpected “loose-internet-connection” randomly.
The setup I have is a Synology 713+ with the expansion box dx513 connected to a Thompson tg789vn.
I discovered that if I ran any services on the Synology NAS with UPNP; connected to the Thompson and too many connections were created in a rapid speed, this would cause the Thompson to bring down the Internet Link.. so the sum of all this is – dont use UPNP. 🙂