I was getting this error in a home network with 2 PCs. 1 PC would play fine while the other was constantly getting the unknown error. I went to my modem/router settings Local Network>DHCP Server>Disable DHCP Server. Have tested this for 6 hours and no error so far. Not sure why this worked for me, but please write down your settings before disabling in case you need to revert back to them. Perhaps someone with a better network knowledge can come up with a less intrusive solution, but if you are desperate for a possible fix then try this.