Some players experience lag and disconnect randomly

Hey everyone, I have a seemingly impossible problem - let's see if someone here can help me. I host a Fabric Minecraft server on my VPS using CraftyController, and every few hours some of the players (who has the problem differs every time) experience a lot of lag and sometimes get kicked. The connection is stable otherwise. The mods used on the server are attached as a screenshot. However, the server seems to still be running fine and CPU, RAM and TPS are all okay. There also isn't a real error in the console, only sometimes after a while it throws:
[21:22:00] [Netty Epoll Server IO #4/WARN]: Failed to deliver packet, sending fallback clientbound/minecraft:system_chat
io.netty.channel.StacklessClosedChannelException: null
at io.netty.channel.AbstractChannel.close(ChannelPromise)(Unknown Source) ~[netty-transport-4.1.118.Final.jar:?]
[21:22:00] [Netty Epoll Server IO #4/WARN]: Failed to deliver packet, sending fallback clientbound/minecraft:system_chat
io.netty.channel.StacklessClosedChannelException: null
at io.netty.channel.AbstractChannel.close(ChannelPromise)(Unknown Source) ~[netty-transport-4.1.118.Final.jar:?]
On a client which is experiencing the problem it throws:
...
[21:20:18] [Netty Client IO #5] [Essential Logger/ERROR]: Network Exception Caught
java.net.SocketException: Connection reset
at java.base/sun.nio.ch.SocketChannelImpl.throwConnectionReset(Unknown Source)
at java.base/sun.nio.ch.SocketChannelImpl.read(Unknown Source)
at knot//io.netty.buffer.PooledByteBuf.setBytes(PooledByteBuf.java:255)
at knot//io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:1132)
at knot//io.netty.channel.socket.nio.NioSocketChannel.doReadBytes(NioSocketChannel.java:356)
at knot//io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:151)
at knot//io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:796)
at knot//io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:732)
at knot//io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:658)
at knot//io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562)
at knot//io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:998)
at knot//io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at java.base/java.lang.Thread.run(Unknown Source)
[21:20:18] [Netty Client IO #5] [Essential Logger/ERROR]: Network Exception Caught
[21:20:18] [Netty Client IO #5] [net.minecraft.class_128/ERROR]: Negative index in crash report handler (13/21)
...
...
[21:20:18] [Netty Client IO #5] [Essential Logger/ERROR]: Network Exception Caught
java.net.SocketException: Connection reset
at java.base/sun.nio.ch.SocketChannelImpl.throwConnectionReset(Unknown Source)
at java.base/sun.nio.ch.SocketChannelImpl.read(Unknown Source)
at knot//io.netty.buffer.PooledByteBuf.setBytes(PooledByteBuf.java:255)
at knot//io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:1132)
at knot//io.netty.channel.socket.nio.NioSocketChannel.doReadBytes(NioSocketChannel.java:356)
at knot//io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:151)
at knot//io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:796)
at knot//io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:732)
at knot//io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:658)
at knot//io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562)
at knot//io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:998)
at knot//io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at java.base/java.lang.Thread.run(Unknown Source)
[21:20:18] [Netty Client IO #5] [Essential Logger/ERROR]: Network Exception Caught
[21:20:18] [Netty Client IO #5] [net.minecraft.class_128/ERROR]: Negative index in crash report handler (13/21)
...
We also noticed that if you move a lot in that moment, you're more likely to get disconnected. I suspect this has to do with the connection to server, and it's caused by the provider - or am I wrong?
No description
4 Replies
LGN
LGN3w ago
Are you using your own hardware or a hosting website
FQQD!!!!
FQQD!!!!OP3w ago
I'm using a hosting provider (https://server.unesty.net, to be exact)
LGN
LGN3w ago
I was going to say if you are using something like playit and self hosting then I would've understood the problem lol
FQQD!!!!
FQQD!!!!OP2w ago
oh, i see. But no, I think it's a hoster problem to be honest... For the record: The issue is seemingly fixed since I edited the SRV DNS record used to point to my Minecraft server to only point to an IPv4-only host domain. Seems like Minecraft, Fabric or one of the mods still doesn't fully work with IPv6.

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