Thank you. Solved. I could never imagine i should change the name to a diferent one listed on Luci. But that was the solution.
I also had to change from pap-secrets to chap-secrets.
#cat /etc/config/pppoe
config pppoe_server
option maxsessions '64'
option optionsfile '/etc/ppp/pppoe-server-options'
option unit '0'
option offset '0'
option timeout '60'
option mss '1468'
option interface 'lan'