Time Machine Backup not working on AX50 on Big Sur

I have a new AX50 and I can't get my backups to work.  It doesn't matter if the USB drive is formatted on HFS+ or APFS.  I've tried the following:

• Different Drives
• Formatting the drive to APFS
  • My Mac can read the drive fine when it's connected directly to it.
  • The AX50 doesn't recognize the drive at all.
    • Does the AX50 even read APFS formats?
• Formatting the drive to HFS+
  • My Mac can read teh drive fine when it's connected directly to it.
  • The AX50 does recognize the drive, but cannot back up.  Through the TPLink GUI, it recognizes the drive.  I've added the drive, turned on sharing and contents to the drive, turned on Access Authentication, created an account and password, and enabled media sharing.
  • Time Machine recognizes the drive, but refuses to backup to it.  It says "Time Machine couldn't complete the backup to "Archer AX50.local"
  • I tried switching to an encrypted backup and that didn't work as well.
  • I can SMB connect to the drive with no issue

I'm on week 3 with tech support and still no progress. Looking for the community to help.  If I can't figure this out soon, I'll be returning this router and going to another brand.