go to wan config
right click on the wan table and click inspect element
click on console
editGPONWan(0,1,3,1) change vlan to 999
apply and close
then type
editGPONWan(0,1,4,1)
change vlan of that to 998
then finally editGPONWan(1,1,1,1)
this is the main one. you can change whatever u want here