The issue at hand was simply that the wireless clients were unable to connect to a 802.1X-enabled wireless network. The clients were authentication themselves to a Microsoft Windows 2003 IAS-server and there had been some work with the certificates prior to this so it was most likely related to the certificates.

First off I was unable to find a Server Authentication Certificate, so I went ahead and issued a certificate.
Still the clients were unable to connect and these errors were spamming the log files.

Output from the log files included

Access request for user localdomain.local\username was discarded.
Reason-Code = 1
Reason = An internal error occurred. Check the system event log for additional information.

In the Systems-log, the following error could be found:

Could not retrieve the Remote Access Server’s certificate due to the following error: The credentials supplied to the package were not recognized

Solution
In order to resolve this issue I had to export the newly issued certificate from the RADIUS-server, delete it from the certificate stores and import it onto the server again.

HTH.