I think it is becuase the server is on proxy
yes it is bungeecord that is causing the issues, however it is here to stay for the time being because its the only way I can do a premium and non premium players to connect to kraftzone.
just keep posting the error messages here I have seen a few myself and while its not great at least the server uptime is actually way better now, so a disconnect and reconnect every now and again isn't so bad.
Hopefully it will be improved in the future.