I'm using our Gigabit Fibre connection for music jamming via the internet. Jamulus is a popular software applications for this. It uses a client-server architecture versus peer-to-peer systems such as SonoBus. If I run the Jamulus client along with a copy of the server on a Windows 10 or Mac machine the performance is very good as would be expected. Latency is 0 -1 ms, the audio is without artifacts. If I connect the client to a private server on the internet the performance is not quite as good. Latency to Seattle for example is 4 - 6 ms with periodic pops in the audio. However if I run a client and a server on different machines on the Actiontec's LAN, the performance is terrible. Why might this be?
There may be an issue with the firewall/anti-virus on the server machine. When client is on the server it bypasses the firewall.