Problemi connessione utenti

Hi, I installed and loaded on my PC a Private Minecraft server to play with some friends online, until a few weeks ago everything worked perfectly, then I had to format the PC where the server was configured and from that day the problems started, I burst out of this series of Warnig attach the file log and we are driven out of the server, are weeks that I slam but I can not find a solution to the problem, someone can help me and understand the reasons?

P.S

I put at random because otherwise I did not complete the post "I do not know what those versions refer to I apologize in advance"

Thank you

----at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:647)
[18:14:47 WARN]: at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:582)
[18:14:47 WARN]: at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:499)
[18:14:47 WARN]: at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:461)
[18:14:47 WARN]: at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884)
[18:14:47 WARN]: at java.lang.Thread.run(Unknown Source)
[18:14:47 WARN]: java.io.IOException: Connessione in corso interrotta forzatamente dall'host remoto
[18:14:47 WARN]: at sun.nio.ch.SocketDispatcher.read0(Native Method)
[18:14:47 WARN]: at sun.nio.ch.SocketDispatcher.read(Unknown Source)
[18:14:47 WARN]: at sun.nio.ch.IOUtil.readIntoNativeBuffer(Unknown Source)
[18:14:47 WARN]: at sun.nio.ch.IOUtil.read(Unknown Source)
[18:14:47 WARN]: at sun.nio.ch.SocketChannelImpl.read(Unknown Source)
[18:14:47 WARN]: at io.netty.buffer.PooledUnsafeDirectByteBuf.setBytes(PooledUnsafeDirectByteBuf.java:288)
[18:14:47 WARN]: at io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:1108)
[18:14:47 WARN]: at io.netty.channel.socket.nio.NioSocketChannel.doReadBytes(NioSocketChannel.java:345)
[18:14:47 WARN]: at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:148)
[18:14:47 WARN]: at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:647)