synology NAS connected on router not "seen" in Orbi wifi system

Hello,

Currently my PC is connected to my router through a Devolo CPL and my Synology NAS is connected directly to the router.

All my other network components are connected through Orbi (the Orbi base is of course connected to the router).

The problem is that in that set up the NAS is not seen by components on Orbi....and if I connect the NAS to Orbi then the NAS is not seen by my PC....

Any idea on how to solve this pb would be much appreciated...

best regards