What layer of the stack do we think this is happening at? I seem to recall that GPON has forward error correction, so the same bit flipping in every packet see

What layer of the stack do we think this is happening at? I seem to recall that GPON has forward error correction, so the same bit flipping in every packet seems unlikely to be caused there. But, I suppose that core routers are complicated enough these days to cause problems like this (custom ASICs doing all the bit moving), and if it affects every customer without common pieces of network equipment in between, it sure sounds like a software problem. More programs, more problems!