My solution, steps:
1) Install the firmware fix DSL-AC68U_9.0.0.4_384_21126-fix01_DSL_1.0.4.6.trx.zip (DSL-AC68U_9.0.0.4_384_21126-fix01_DSL_1.0.4.6.trx) in rescue mode and / or from http://192.168.1.1
2) Factory reset
3) DSL (Internet does not connect) then the DSL LED does not turn on
4)...