Well I talked too soon!
It turns out that now this Ubuntu 16.04.3 LTS guest as well as all others too have lost their network connections!
To me this looks like a serious bug in the PRO 12.5.8 version, at least when running in a Windows 7 X64 Pro workstation like mine!
This time, what triggered the issue (at least this is what I believe) is that I configured DHCP on my router (an ASUS RT-AC68U) to reserve IP addresses for the bridged guests.
When I applied this the router sort of recycled and the network connections went down for a few seconds.
After this nothing network wise works on the VMWare Workstation PRO 12.5.8 anymore, not even closing and starting it again makes the guest networking work..
Last time (when I started this thread) the problem was initiated by me upgrading WS PRO12 to the latest version 12.5.8 and since it did not suggest that a restart was needed I proceeded but got these errors. A full system restart worked to get back to normal.
But now I have the same situation without even changing anything at all in PRO12, when the router network glitch happened both running guests lost their network connection and it was not fixed by rebooting the guests nor by restarting PRO12!!
QUESTION:
Can I downgrade to PRO12.5.7, which has worked fine for a long time? Or am I hosed after upgrading to 12.5.8?
Now I must close all of my working windows and reboot my whole system just to see if this will solve anything.
What a pain!
After the reboot I will test and then report back here.