PPPoE.
PPPOE Users Lost IP and Convert To D in Interfacelist without any reason
There is no traffic on some clients, not at all.
To customers without traffic, on PPPoE, the first column is showing a D and not a DR. and some user active and show DR ? 
First, I would like to see your configuration. Otherwise there’s nothing to talk about
Check you haven’t run out of IPs in pool AKA more clients than IPs .. it does weird stuff when that happens 