After added the JBoss remote repository in Apache Archiva, You have to add the proxy connector in Archiva as well.

Steps of add proxy connector in Apache Archiva

1) Log in as admin to your Archiva server , e.g http://localhost:8888/archiva/

2) Click the “Proxy Connectors” under Administrator group option

3) Click on the small “Add” link

4) Fill in the proxy connectors information

Network Proxy : Choose direct connection or proxy if you are using it
Managed Repository : Say no to snapshots
Remote Repository : Choose your remote repository here (JBoss from previous article)

5) Done

Reference

Proxy connectors – http://archiva.apache.org/docs/1.0.2/adminguide/proxy-connectors.html