This may sound silly: Out of habit, I gave my new Nucleus a static IP and network settings.
To my surprise, roon software on Mac and iPhone is sluggish sometimes discovering the core.
A friend recommended leaving it as DHCP and thus “Nucleus”.
Personally, I would use DHCP every time. If I wanted a device to always have the same IP address, I would use the router’s DHCP server to reserve the address, and not use static addresses on the devices.
Just try it. If it remains the same your issues are elsewhere and we can come back to it. It is by no means a given that your problems are related to the fixed IP.