@BigE0n I think it might be my ISP, but when I switched to a different master deco, I got no connection at all. I wonder if my ISP registered the MAC address of my master deco and wouldn't let...

@Tony Thank you. Deleting all the nodes from the network in the Deco app, then restarting everything fixed my issue.

I have a Deco M5 V1 (three units). All are connected via cat-5 wiring. Internet comes from the cable modem to the primary M5, then out from the primary M5 to a network switch where it gets sent to...