[gregmac]

It's good to move to Zigbee/thread/z-wave anyway because they're all better protocols for smarthome stuff. Plus wifi means you might be buying stuff that relies on cloud, which is a non-starter for anyone that doesn't like buying future paperweights.

But your criticisms are strange. You have more than 254 devices connecting (which implies a complex setup) but can't increase the subnet size? Or does your router just have an absurdly small default DHCP range?

I also don't understand the swap your router problem, unless you're also using default SSIDs and not changing it. Configure the SSID and PSK to be the same as before and everything will just work.