OK here's the deal I have W7 and W10 guests running under VMWare WS Pro. They are using bridged networking and DHCP, and they used to work fine. It's some while (over a year) since I last used these guests.

Now I try to use them and they all give me "Unidentified Network" when I try to enable the NIC in the VM

If I set to use Static IPs they are happy as larry, as does NAT networking.

How to find out what's actually going wrong here ? I don't want a "try this" or "try that", I want a definitive this happens and then that happens (or doesn't as the case may be). Windows 98SE, Windows XP and Linux guests are all working fine with DHCP ...