Orbi Problems with remote controll of UPNP / DLNA renderers

The actual model I have is Orbi RBK22-100NAS. When I installed it it auto-updated firmware now running V2.4.12.869

I replaced my ASUS router with an Orbi System. I have a Synology NAS connected to the router (Ethernet wired port).  Throughout the house i have several DLNA / UPNP rendering devices such as Grace Digital streamer, RKM Streamer,...  I also have 2 PC devices running Foobar2000 with the renderer add-in. I use this to stream my ripped music collection.

Before I replaced the Orbi, I could use any Remote DLNA application to stream anywhere in the house.  Not the case any more.  When I open Synology DS Audio app, first off I cannot see any Foobar2000 machine (even though they can stream standalone), I can stream on the RKM with a lot of inconsistency (whenever I succeed at streaming it freezes after a few songs) and I am luck if I can stream on the Grace Digital box at all. 

Also, the Audio Station app on Synology has a hard time "pushing" the music to those devices when the app is used as remote controller. 

Doing some research, I deactivated the daisy-chain feature on advanced setup, I disabled IPv6, and I unchecked the option "Enable 20/40 MHz Coexistence".

The UPNP option is turned on on the Orbi.  the UPnP Portmap Table only has the IP address correspoinding to the Synology. I wonder if other devices should show here, but there's no option to add anything.

The signal in the house with Orbi is good but this is a dealbreaker.  If I can't stream this is going back and I would get a router.

I appreciate any help! You may imagine I can't live without music!