Automatic routing filter rejected remote request - Nexus

Automatic routing filter rejected remote request - Nexus

I'm trying to get the netty-codec-hhtp going in my maven project. I have a
completely standard Sonatype Nexus set up to proxy requests to Maven
Central.
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-codec-http</artifactId>
<version>4.0.9.Final</version>
</dependency>
This fails when building using maven. If I search for it manually in Nexus
I find it, but if I go to download the jar it tells me:
404 - Not Found
Automatic routing filter rejected remote request for path
/io/netty/netty-codec-http/4.0.9.Final/netty-codec-http-4.0.9.Final.jar
from M2Repository(id=central)
What does this even mean, why am I getting it, and maybe more importantly,
how do I fix it? I am using Nexus 2.5.0-04 with Maven 3.0.4
Downloading other artifacts seems to work just fine.