Casual lost packets on my RB

I have one CCR1009 ( firmware 6.46.4 stable) in PCC load balance configuration with pppoe server.
Every 1, 2, 3, 4 hours, start loss packets for 10/20 seconds, in casual mode. Cpu load 1%
I try connection without pppoe authentication and the same happens, I try replace cable gigabit, I try replace power supply
I don’t know where the investigate, someone else had a similar problem?