Today there has come up a new thread by another user who experiences the same problem:
On that thread, @danny from Roon brings up the question if the user has previously set up a static IP on his Nucleus… Thing is, if this is not done right (configuring the router’s DHCP service to keep this IP reserved for the Nucleus), at any time the router’s DHCP service could assign this same IP to another device on the network, which always leads to problems. To avoid such problems, it’s better to just let the Nucleus ask the DHCP server for its IP, and set up on the router the address reservation.
So Alan, this of course could possibly also be the underlying problem in your case. Do you remember having set up at any point of time in the past a static IP for the Nucleus on the Nucleus WebUI?
If so, now that the Nucleus is disconnected from your network, if you try to ping the known IP of the Nucleus, what’s the output? If you’re still up to make this probe, you can again try to ping the known IP from the Terminal app on your Mac:
ping -c 10 192.168.1.175