[FS#656] IPv6 relay mode does not work

[LEDE Bugs]

The following task has a new comment added:

FS#656 - IPv6 relay mode does not work
User who did this - clockbox (mlongbrake)

----------
I increased the logging verbosity as requested.  In the process I discovered that restarting odhcpd makes it work correctly, it just does not work directly after bootup.

The attached file "pre-restart.txt" is the logread output after bootup.  It appears that odhcpd is receiving packets but not doing anything with them.  The first set of requests coming from ...:6789 are my laptop.  I then turned on my Android phone around 18:57:30 and you can see the requests from it as well.

I then turned the phone off again and issued "/etc/init.d/odhcpd restart". I turned the phone on again around 19:00:00.  In "post-restart.txt" the logread shows that odhcpd is now properly relaying requests and my phone now gets two IPv6 addresses.  I did manage to get my laptop to obtain an IPv6 address once, but it hasn't been reproducible.  I don't think it's an odhcpd problem though, I'm just not sure how to force Windows to try IPv6 again.

Based on this information, it seems like odhcpd is starting up in a weird state by default.  Restarting it once the router is up and running seems to fix it. 
----------

One or more files have been attached.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=656#comment2294