mjw
(Here I am with a brain the size of a planet and they ask me to pick up a piece of paper. Call that job satisfaction? I don't.)
2
There appears to be an error in your diagram, i.e., WAN and LAN appear to be on the same subnet.
Although I’m not familiar with the Google products, I’d have thought that you could use the same DHCP server, and therefore same subnet, for Wi-Fi and wired networks (or have Roon devices on a VLAN sharing the same subnet.)
You can’t unless you put it in bridge mode which stops the mesh working.
@Arvid_Kristoffersen you need to have all devices on the same network subnet which you don’t currently have using the Google Mesh. Roon will not work over different subnets. You need a mesh system that can get DHCP from your main router and not run its own separate network.
Thanks for reaching out and welcome to the forum! Have you been able to follow the suggestions made by @mjw /@Simon_Arnold3 , or are you still having difficulties here? For reference, here is also the Networking Best Practices guide:
Please keep in mind that Roon does not work properly across subnets, so you would want to ensure that your Roon Core + audio gear you wish to use with Roon are located on one subnet. Hope this helps!