The logs "Failed to create an address entry in pool _DAP" indicate that the duplicate protection feature (Duplicate Address Protection) is preventing a user to come online.

This DAP check is done by JUNOS and will prevent subscribers to come online when they are assigned an IP address by the RADIUS server that is already in use by another subscriber.

Subscribers will be denied access and the following log will be printed:

authd[xxx]: Failed to create an address entry in pool _DAP

If you activate the authd traceoptions (set system processes general-authentication-service traceoptions ...), the following messages can be seen:

Oct 31 15:56:03.952595 Trying to assign address 10.1.1.1 to subscriber session-id:75476368

Oct 31 15:56:03.952613 Unable to create address entry

Oct 31 15:56:03.952625 Failed to create an address entry in pool _DAP

Oct 31 15:56:03.952657 Result have been returned with opcode=0, result=13

<...>

Oct 31 15:56:03.952842 UserAccess:[email protected] session-id:75476368 access-denied BNG#<ACI+ARI>

Oct 31 15:56:03.952855 Setting terminate ID to 30002

If you then lookup the IP address that it tried to assign, you will find it indeed already in use by another subscriber:

user@BNG> show network-access address-assignment pool _DAP | match 10.1.1.1

10.1.1.1     DE:AD:BE:EF:12:23 [email protected] pppoe

user@BNG> show subscribers address 10.1.1.1

Interface       IP Address/VLAN ID           User Name           LS:RI

pp0.3221225495    10.1.1.1                [email protected]   default:default

*           2003:1337:0:4::/64

RADIUS server should be checked and corrected in order to not get duplicate addresses assigned