diff --git a/codec-http2/src/main/java/io/netty/handler/codec/http2/Http2MultiplexCodec.java b/codec-http2/src/main/java/io/netty/handler/codec/http2/Http2MultiplexCodec.java
index e03abd2165..83d9eb5ce7 100644
--- a/codec-http2/src/main/java/io/netty/handler/codec/http2/Http2MultiplexCodec.java
+++ b/codec-http2/src/main/java/io/netty/handler/codec/http2/Http2MultiplexCodec.java
@@ -305,6 +305,12 @@ public final class Http2MultiplexCodec extends ChannelDuplexHandler {
         }
         channel.pipeline().addLast(handler);
 
+        // We need to copy parent's channel options into a child's options to make
+        // sure they share same allocator, same receive buffer allocator, etc.
+        //
+        // See https://github.com/netty/netty/issues/6551
+        channel.config().setOptions(parentChannel.config().getOptions());
+
         initOpts(channel, options);
         initAttrs(channel, attrs);
 
diff --git a/codec-http2/src/test/java/io/netty/handler/codec/http2/Http2MultiplexCodecTest.java b/codec-http2/src/test/java/io/netty/handler/codec/http2/Http2MultiplexCodecTest.java
index 95e57a5e24..c17c1970da 100644
--- a/codec-http2/src/test/java/io/netty/handler/codec/http2/Http2MultiplexCodecTest.java
+++ b/codec-http2/src/test/java/io/netty/handler/codec/http2/Http2MultiplexCodecTest.java
@@ -39,6 +39,7 @@ import org.junit.Before;
 import org.junit.Test;
 
 import static io.netty.util.ReferenceCountUtil.release;
+
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
@@ -343,6 +344,28 @@ public class Http2MultiplexCodecTest {
         assertEquals("bar", channel.attr(key).get());
     }
 
+    @Test
+    public void childChannelShouldShareParentsChannelOptions() {
+        EmbeddedChannel parent = new EmbeddedChannel();
+        parent.config().setAutoRead(false);
+        parent.config().setWriteSpinCount(42);
+
+        Http2StreamChannelBootstrap b = new Http2StreamChannelBootstrap();
+        parent.pipeline().addLast(new Http2MultiplexCodec(true, b));
+
+        Channel child = b
+            .parentChannel(parent)
+            .handler(new TestChannelInitializer())
+            .connect()
+            .channel();
+
+        assertFalse(child.config().isAutoRead());
+        assertEquals(child.config().getWriteSpinCount(), 42);
+
+        child.close();
+        assertTrue(!parent.finish());
+    }
+
     @Test
     public void outboundStreamShouldWriteGoAwayWithoutReset() {
         childChannelInitializer.handler = new ChannelInboundHandlerAdapter() {