I was having DNS issues yesterday using cloudflare’s DoH, so I’m curious if it is going to be related.

I’ve had the same experience you describe with Zwave, especially the range and response issues, and in hindsight should have used the already reliable WiFi network. Especially since our home layout is a bit unconventional and node placement is not ideal considering the Zwave hop limits. For battery devices that consideration might be different, but I try to avoid those anyway.