[Sephiroth]

IMO, the correctables arise from four potential sources:

1/
Faulty modem (unlikely but possible)

2/
Noise ingress particularly at/from the street cabvinet to your modem. This would occur only if there was an RF situation caused by CB radio finding a strand of wire sticking out, maind feedback from another house, water in the wall box or tap box.

3/
Something going on in the wider VM network perhaps of the nature in #2 above.

4/
I'm not sure about this one but if there is no FEC mechanism in the routers other than CMTS, then any bit werror occuring in transport will only be detedted at your CM. That error could come from data source.