This is why, in my case, the ISP's router (that awful box Verizon provides with FIOS) is sitting, beside the DMARC, unplugged and powered off. My DMARC has a h

This is why, in my case, the ISP's router (that awful box Verizon provides with FIOS) is sitting, beside the DMARC, unplugged and powered off. My DMARC has a hot ethernet jack, and my firewall (PC running Linux) that I control is connected to that ethernet jack. No ISP shenanigans (other than what they can remotely do to configure the FIOS DMARC itself).