Cant change Networks

Super frustrated and should not be. I have been running Home Assitant for several years on a Raspberry PI 4 and all was well until I wanted to change the IP address range that my HA is running on. I want to move it from a 192.168.168.X to a 192.168.100.x network. It wont accept any IP address in that range from my router. I can set it manually but then I have no network connectivity at all. Getting it to take any IP in the 192.168.168.X range is not a problem with DHCP or static. What is the trick? I have never had any issue in the past with any other devices…this is a first.

I just set a static IP in the HA settings like so:-

If your router is configured to issue IP addresses in the range you need, and you can’t see HA connected to it, then it might be a few things:-

The IP is already assigned to another device.
You have an address reservation rule in the router for the old IP.