Having trouble setting up Hyper-Backup between two NASs on the same LAN

I have two 4-bay Synology NASs and I’m tryng to setup Hyper-Backup from the primary to the secondary.

With the two NASs on different routers behind the same cable modem, the system works, however, if I put them both on the same router, same network, I get the following when trying to configure the backup task:

“Failed to connect to the backup destination. Please make sure:

1. The hostname/IP address/port of the backup destination is correct.

2. The backup service is enabled on the backup destination. For backup to a remote Synology storage system, Hyper Backup Vault should be installed and running on the destination.

3. The backup destination has proper network connection.

4. If the backup destination is behind a NAT, please make sure the port forwarding rules have been configured on the NAT.

5. If the backup destination is behind a firewall, please make sure Hyper Backup service is allowed by the firewall rules.”

This is after the server (secondary NAS) was found on the network and I successfully logged into it.
Both NASs are on 192.168.0.x and I have the issue - if one is on 192.168.1.x and the other is on 192.168.0.x it works successfully. I’m trying to have my NASs NOT be on the IoT network where I want network isolation turned on. On the primary network 192.168.0.x, network isolation is not enabled.
Because it works when they are on different networks, I don’t think it is a user / permissions issue… Also, The vault is running on the secondary NAS just like when it is on the other network/router.

Any suggestions?

Thank you in advance, Tom

I found a workaround for the task setup not working…

I edited the old task to use the new (same network) IP address for the destination NAS and all was good…

Tom