I am experiencing the same problem with CCA 3.0.1 (EN) and a new SR520W (Fast Ethernet) router.
Attached is a screen shot of the point of failure in the CCA Device Configuration Wizard.
In the Wizard, clicking the Modify button in the WAN configuration page is a repeatable show stopper.
Please let me know with this bug is fixed. Until then, I will need to do the Device Configuration using a command line terminal.
Arnold