IPv6 causing crashing because of inability to forward packet

[fgtfv567]

My N305 router will crash about once a week and be forced to restart. The error message given is fatal trap 12: page fault.

In System > Log Files > General, I keep seeing a similar message saying an IPv6 packet can't be forwarded. Here's an example of one of the many lines I'm seeing:

<7>cannot forward src fe80:1::ce6e:a4ff:fef9:90e9, dst 2600:1406:3a00:1f::173e:2e78, nxt 6, rcvif igc0, outif igc1


If I turn off these two settings below in System > Settings > Tunables, the above messages go away and the router doesn't crash.
net.pf.share_forward6
net.inet6.ip6.forwarding

What is going on and how do I resolve it so I can keep IPv6 connectivity?