cause: the previous rp-pppoe was built without kernel mode PPPoE support.
Consequence: it's not possible to use kernel mode in pppoe-server. The pppoe-server doesn't load the plugin p-pppoe.so.
Fix: the new rp-pppoe version is now built with kernel mode PPPoE support, so that the pppoe-server now can load the plugin rp-pppoe.so.
Result: the kernel mode PPPoE now can be used