The current DHCPV6 agent implementation cannot delegate agent operations to the PPPOE interface prefix, such as the following directives:
```
listen-interface br1.2 {
address FF02::1:2
}
max-hop-count 10
upstream-interface pppoe0 {
address FF02::1:2
}
use-interface-id-option
```
The expected behavior of the configuration is that the subordinate devices of BR1.2 are expected to delegate requests to PPPOE via the DHCPV6 prefix in order to complete the prefix delegate, but the actual situation is:
```
vyos@vyos# sudo /usr/sbin/dhcrelay -6 -pf /run/dhcp-relay/dhcrelay6.pid -l FF02::1:2%br1.2 -u FF02::1:2%pppoe0 -c 10 -I
Internet Systems Consortium DHCP Relay Agent 4.4.1
Copyright 2004-2018 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/
Bound to *:547
Listening on Socket/br1
Sending on Socket/br1
Listening on Socket/eth5
Sending on Socket/eth5
Listening on Socket/eth4
Sending on Socket/eth4
Listening on Socket/eth3
Sending on Socket/eth3
Listening on Socket/eth2
Sending on Socket/eth2
Listening on Socket/eth1
Sending on Socket/eth1
Listening on Socket/eth0
Sending on Socket/eth0
Unsupported device type 512 for "pppoe0"
If you think you have received this message due to a bug rather
than a configuration issue please read the section on submitting
bugs on either our web page at www.isc.org or in the README file
before submitting a bug. These pages explain the proper
process and the information we find helpful for debugging.
exiting.
```