Hi,
After the expansion of IPv6 in our network, we encountered a problem with the occasional break-up of OSPFv3.
For example, when the router reboots or a failure of lines, it will stop the router to work with some neighbors in OSPFv3.
Flapping in ExStart, Loading and 2-Way state.
Usually just shut down OSPFv3 on flapping neighbors and then turned on one by one at intervals of 60 seconds.
Alternatively, shut down OSPFv3 on all routers in the broadcast area network and switch on the same procedure.
Tested with RoS : 6.35 , 6.34.1 , 6.33 , 6.27 , 6.24.

The same problem we had with the QUAGGA. And I solved it as recommended here : https://wiki.quagga.net/wiki/index.php/TipsNTricks , section : Useful command line switches (Linux) , problem with small receive buffer size !!

Thanks for solving the problem.

Moly