I am also having this issue - it seems that Roon loses the Linn Subnet (it reverts to 127.0.0.0, with no other option on the subnet dropdown) when the iMac sleeps. It used to be that I had the iMac go to sleep on a schedule every night, which meant that I usually had to restart the core before using it every day. However since I updated my iMac to the Ventura macOS, the scheduling option has been removed and it sleeps whenever it is inactive for more than a set period. As the roon core does not inform the macOS that it is busy while playing (e.g. from an iPad controller to the Linn DS), this can happen in the middle of playing music. Getting the Linn audio zone back means I have to go to the iMac, wake it up and restart the core. Far too hard!
So what I would like is:
a) don’t let the iMac sleep if music is playing via roon (even a wake up each time the user interacts with a controller connected to the core would do)
b) If you can’t fix the lost subnet issue with the Linn, at least let me type in the subnet to reset the connection. The restart is even more irritating than the bug in your software that loses the subnet in the first place.