Comment # 29 on bug 1017936 from Matthias Gerstner

For all I know the correct configuration using FW_FORWARD as outlined in c#24
should fix this issue.

Remotely debugging why there was a regression when switching from USB to
internal NICs is beyond the scope of the support I can offer. The important
bit is to get the configuration right.

Since there's no response to my suggestion I think the situation is under
control and I'm closing the ticket.