How often are those ra-updated calls happening? They happen when odhcp6c receives new RA (router advertisement) from your ISP, but there are problems; see my own problem for reference: Odhcp6c issue with my ISP's configuration
If the RAs you're receiving aren't a mess like mine, you can delay these by setting this /etc/config/network, wan6 interface:
option ra_holdoff '180'
180 being the number of seconds to ignore identical RAs. Set it to whatever you feel like.