I'm playing Minecraft with two other people. The problem is that one of my friend keeps getting kicked out of my server. The server outputs the disconnection as

TranslatableComponent{Key='disconnect.genericReason',args=[Internal Exception:java.io.IOException: An establish connection was aborted by the software in your host machine],siblings=[] style=Style{hasParent=false, color=null, bold=null, italic=null,underlined=null,obfuscated=null,clickEvent=null,hoverEvent=null,insertion=null}}

After that, when he tries to log in, he'll log in and get timed out after a while, and then he gets kicked off of the server but list still says he is online and his character is there too. It just keeps repeating and restarting the server doesn't really help at all. When I restart the server, the first person that joins doesn't get the error while the other one does which is really weird. I have been told to reset the player dat files but that hasn't done anything. Any solutions?