I would say that it is a great router but a poor NAS.

@S-Cote formating option on the Archer or Seagate ?

@S-Cote My New NAS system from Segate works like a charm, hourly backup since May, zero issue.

@yavoh000 I finaly give up. Even if setting the RW permission allowed me to see rhe disk as a time machine disk, it worked for a day and then the disk was locked. I have reformatted the disk a couple...

Thanks for the hints. It works well here, after changing the R&W access on the disk. I am surprised that my external disk, which was originally mounted on an Airport extreme, is format which Apple...