If TCP-MD5 keymapping extends 256 peers following error occurs:

java.lang.IllegalStateException: channel not registered to an event loop
at io.netty.channel.AbstractChannel.eventLoop(AbstractChannel.java:116)[69:io.netty.transport:4.0.37.Final]
at io.netty.channel.epoll.AbstractEpollChannel.doDeregister(AbstractEpollChannel.java:132)[73:io.netty.transport-native-epoll:4.0.37.Final]
at io.netty.channel.epoll.AbstractEpollChannel.doClose(AbstractEpollChannel.java:109)[73:io.netty.transport-native-epoll:4.0.37.Final]
at io.netty.channel.AbstractChannel$AbstractUnsafe.closeForcibly(AbstractChannel.java:638)[69:io.netty.transport:4.0.37.Final]
at io.netty.bootstrap.AbstractBootstrap.initAndRegister(AbstractBootstrap.java:312)[69:io.netty.transport:4.0.37.Final]
at io.netty.bootstrap.AbstractBootstrap.doBind(AbstractBootstrap.java:272)[69:io.netty.transport:4.0.37.Final]
at io.netty.bootstrap.AbstractBootstrap.bind(AbstractBootstrap.java:268)[69:io.netty.transport:4.0.37.Final]
at io.netty.bootstrap.AbstractBootstrap.bind(AbstractBootstrap.java:257)[69:io.netty.transport:4.0.37.Final]

io.netty.channel.ChannelException: setsockopt() failed: Cannot allocate memory
at io.netty.channel.epoll.Native.setTcpMd5Sig0(Native Method)[73:io.netty.transport-native-epoll:4.0.37.Final]
at io.netty.channel.epoll.Native.setTcpMd5Sig(Native.java:243)[73:io.netty.transport-native-epoll:4.0.37.Final]
at io.netty.channel.epoll.TcpMd5Util.newTcpMd5Sigs(TcpMd5Util.java:69)[73:io.netty.transport-native-epoll:4.0.37.Final]
at io.netty.channel.epoll.EpollServerSocketChannel.setTcpMd5Sig(EpollServerSocketChannel.java:130)[73:io.netty.transport-native-epoll:4.0.37.Final]
at io.netty.channel.epoll.EpollServerSocketChannelConfig.setTcpMd5Sig(EpollServerSocketChannelConfig.java:167)[73:io.netty.transport-native-epoll:4.0.37.Final]
at io.netty.channel.epoll.EpollServerSocketChannelConfig.setOption(EpollServerSocketChannelConfig.java:73)[73:io.netty.transport-native-epoll:4.0.37.Final]
at io.netty.channel.DefaultChannelConfig.setOptions(DefaultChannelConfig.java:113)[69:io.netty.transport:4.0.37.Final]
at io.netty.bootstrap.ServerBootstrap.init(ServerBootstrap.java:153)[69:io.netty.transport:4.0.37.Final]
at io.netty.bootstrap.AbstractBootstrap.initAndRegister(AbstractBootstrap.java:310)[69:io.netty.transport:4.0.37.Final]
at io.netty.bootstrap.AbstractBootstrap.doBind(AbstractBootstrap.java:272)[69:io.netty.transport:4.0.37.Final]
at io.netty.bootstrap.AbstractBootstrap.bind(AbstractBootstrap.java:268)[69:io.netty.transport:4.0.37.Final]
at io.netty.bootstrap.AbstractBootstrap.bind(AbstractBootstrap.java:257)[69:io.netty.transport:4.0.37.Final]