How to set-up roon core direct link to bridge with a single LAN wire?

I want to skip music stream transit from a router.
Is it able to setup local network between core and bridge with a lan wire attached to both ends?

Yes , this configuration is supported . You need two distinct Ethernet interface on server/core , First one connected to the router and second one to bridge appliance …

If you have a switch in addition to a router in your network It’s good enough to properly configure static gateway on your “Roon net only” nodes.

no router in the layout. Just LAN to LAN port, one core, one bridge, one lan wire. I have succeeded link HQplayer and NAA in this way thinking that roon core and bridge works also the same way.

Sorry - but this looks contradictory …

That won’t work if you are using ropieee as an endpoint btw. Ropieee needs to get a time from the internet during boot.

YES,i make it working in this way. Install Linux + roon server and Linux + roon bridge to 2 mini pc, then link 2 LAN interface with one wire. internet gateway is roon server. attach usb dac to roon bridge.

I don’t use Ropieee. just Linux OS , roon server and bridge.

You will get better sound quality with direct link between roon server and bridge.

Roon needs access to the internet to check for licensing from time to time. You will find it just wont one day if you are using a closed system. Your also going against what its designed to do.

Not necessarily true.

I use a dual-lan port mini pc as roon server in the system setup.
roon server
LAN 1 for internet connection. I think roon server check its license from time to time, not the bridge end point.
LAN 2 direct connect to roon bridge LAN port and share the internet connection.

in above setup roon bridge connected to internet through roon server host.