[Netty Server IO #2/ERROR] [FML]: NetworkDispatcher exception

so me and my friend have been playing on a sky odyssey server I set up. it generally has been going ok, until he got kicked from the server and my pc lost internet (I have ethernet plugged in, and all my other devices still had wifi) and the console kept giving this error.

[07:49:42] [Netty Server IO #2/ERROR] [FML]: NetworkDispatcher exception
java.io.IOException: An existing connection was forcibly closed by the remote host
        at sun.nio.ch.SocketDispatcher.writev0(Native Method) ~[?:1.8.0_281]
        at sun.nio.ch.SocketDispatcher.writev(Unknown Source) ~[?:1.8.0_281]
        at sun.nio.ch.IOUtil.write(Unknown Source) ~[?:1.8.0_281]
        at sun.nio.ch.SocketChannelImpl.write(Unknown Source) ~[?:1.8.0_281]
        at io.netty.channel.socket.nio.NioSocketChannel.doWrite(NioSocketChannel.java:432) ~[minecraft_server.1.12.2.jar:?]
        at io.netty.channel.AbstractChannel$AbstractUnsafe.flush0(AbstractChannel.java:856) [minecraft_server.1.12.2.jar:?]
        at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.forceFlush(AbstractNioChannel.java:368) [minecraft_server.1.12.2.jar:?]
        at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:618) [minecraft_server.1.12.2.jar:?]
        at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:559) [minecraft_server.1.12.2.jar:?]
        at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:476) [minecraft_server.1.12.2.jar:?]
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:438) [minecraft_server.1.12.2.jar:?]
        at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858) [minecraft_server.1.12.2.jar:?]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_281]

im not that good with servers so im not too sure how to fix it.