I have been having a lot of issues with my Minecraft server.  It used to work perfectly and then suddenly everyone joining off local network would get kicked off with an error that always starts with, "Internal Exception: io.netty.handler.codec.DecoderException" but then ends in something different every time.  Sometimes they are just kicked once and then can rejoin, but sometimes they are basically soft-banned from the server where they get this error every time they join.  It has essentially made my server unplayable.