Snapshot vault failed

Dear All,
Problem:

Was unable to setup SnapVault Replication after update to latest firmware 5.2.4 3092.
Both Qnap’s are TS-431XeU with latest firmware

Setting up the Replication Job from Qnap A to Qnap B always resulted in the infamous "Failed to connect.
Qnap B to Qnap A is working fine.

Checked:

  • SSH and SFTP were enabled on target system

  • used an Admin (not default) account

  • Password was correct

  • Port was set correctly

  • Target IP was correct

  • SourceSystem not on DenyList

DoubleCheck:

  • SSH Login from PC/MAC to Target works.

Loggin into SourceSystem via SHH and executed:

su rm /root/.ssh/known_hosts