Not all log entries are errors.
Apr 19 08:05:30 kernel: bcm_mcast_mld_add:833 mc_fdb->rep_list ffffffc0191d0ba8 next ffffffc01e888460 prev ffffffc01e888460 rep_entry->list ffffffc01e888460 next ffffffc0191d0ba8 prev ffffffc0191d0ba8
This appears to be a host joining a multicast pool. The router appears to be logging the list of hosts as they join the pool.
Completely normal operation.
Apr 19 08:05:30 kernel: bcm_mcast_mld_add:833 mc_fdb->rep_list ffffffc0191d0ba8 next ffffffc01e888460 prev ffffffc01e888460 rep_entry->list ffffffc01e888460 next ffffffc0191d0ba8 prev ffffffc0191d0ba8
This appears to be a host joining a multicast pool. The router appears to be logging the list of hosts as they join the pool.
Completely normal operation.