Same thing for me... Always lose W&R option... and nobody understand why...

@S-Cote 

I've identified the problem and notified TP-Link tech support. While it's on my AX6000 I am pretty sure it's across all platforms. The problem is that by default, if formatting HFS+ extended (both case and non case sensitive) it also formats journaling. The router cannot handle the journal, and overwrites it corrupting the filesystem. To fix, disable the journal. On your mac after formatting, mount the drive and get a command line (open terminal). Assume that your drive is named NameOfYourDisk. nter the following command at the prompt:

diskutil disableJournal /Volumes/NameOfYourDisk

Eject the drive and then attach it to the router - that should do the trick. Obviously, test this yourself on something that does not have important data as formatting will wipe it.

And equally important - without the journal, a power outage or reboot while the disk is being written has a chance of causing filesystem damage that you will need to connect to the mac to fix. 

Typical disclaimer applies: I'm not a TP-Link employee, and your milage may vary, but it's working for me.

By the way.. for everyone that says the various solutions that don't involve disabling the journal work - have you tested your backup? By tested, I mean power cycle the router, then restore a file or 20 from your backup. I thought everything was fine until I rebooted the router. When I connected the drive to my mac directly, it reported disk errors it could not fix.