[FS#360] Regression: no ipv6 with multiple interface

[LEDE Bugs]

For full information about what has changed in this task, visit the URL below and click the History tab.

FS#360 - Regression: no ipv6 with multiple interface
User who did this: Hans Dedecker (dedeckeh)
Assigned To: [-] -> Hans Dedecker

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=360