En éditant les NAT FTP de mon Orbi RBR50 je tombe systematiquement sur Error 404

I have an RBR50 V1

I need to redirect ports for my NAS connected to an RBS

my previous NAS was connected on 1.0.0.10 and still connected

I want to use from the outside the new NAS (for cyber concern)

this one is in 1.0.0.20

I have edit easily the http rule only by changing the target

But now it is impossible to change FTP rules : Orbi system always returns error 404

By the fact some services are not available

I would appreciate not to have to return to factory settings one other time

Any one has an explanation or may help

Thanks in advance