Server 2019 Preview 17623: DNS & WDS service issues

I ran some new domain making/configuring PS scripts on this preview. These are well-tested/used on Server 2016 and exercise quite a lot of different areas. I hit two obstacles:

 

1. DNS Service. Doesn't talk to anything (DNS MMC & PS cmdlets just hang, Netlogon logs error events for DNS RR registration failures.) unless you have IPv6 ticked in the NIC properties.
2. WDS Service. Installed OK. After a wdsutil command to authorise it, I then restart the service and it got stuck Starting. The service was Started after a full server restart, but the WDS MMC hangs trying to talk to it.

May yet be issues when I get around to using some of what's been configured, but they're the only things that upset a couple of thousand(!) lines of PS configuration.