I don't get it. My ethereal trace pretty much matches Jerz's, right up to the point that riot should start talking to the server. On Jerz's I can see it talking to the server, on mine nothing happens.

I have turned on the logging in ARM, that shows that all the files get loaded over NFS without error.

The riot binary is clearly running, because the splash.rio file gets fetched over NFS and shown.

I really can't think what else could be going wrong.