Hi Philipp,
welcome to the forum :)
The thing is that you can use different approaches from a remote client.
In your case you should drop 'java:' from the JNDI name, this should work.
The prefered approach is the 'ejb:' prefix which use the ejb-client (and not the remote-naming as you did).
You should have a look to the documents:
ejb-client) https://docs.jboss.org/author/display/AS72/EJB+invocations+from+a+remote+client+using+JNDI
remote-naming) https://docs.jboss.org/author/display/AS72/Remote+EJB+invocations+via+JNDI+-+EJB+client+API+or+remote-naming+project
and you can find some examples here:
https://github.com/wfink/jboss-as-quickstart/tree/ejb-clients/ejb-clients
I hope that helps.