New backend. How to connect?

I am actually having problem with registration for ABP:
ttnctl devices register personalized 002A5BEF a2ffbe227bf5d86885fd81b0204bd79f 03d1d244dff6b93465eb190bb4749821
FATAL Could not register device error=rpc error: code = 2 desc = Invalid operation: rpc error: code = 2 desc = Invalid operation: Unauthorized