DHCP broken for Mac OS catalina

What I usually have found in terms of networking issues is that

some network preference gets borked. What I have done is under

System Preferences->Network, create a new "Location", select the

interface on the left, then click "Advanced..." and on the TCPIP

pane set the DHCP and then click renew lease.

If you are using WiFi, delete the connection and connect again.

sakura240 wrote:

Agree with you that Apple FW issue is a big miss.

You’re misinterpreting my skepticism.

DHCP testing is inherent in accessing most any network, and would be tested in a vast number of networks.

Which leads to investigating what might be unique about this network, this DHCP server, and related details.

That's why we are going to get back and continue to troubleshoot on Sunday. I have a work aorund at this time with using Netbarrier instead. Apple FW is only and application layer FW anyway, a bit lacking in granularity but I'd like to understand why it was broken after the update. It is definitely not Netbarrier issue as we able to eliminate that as a culprit in the troubleshooting process.

So to confirm, you’ve tried this DHCP request on your network without any add-on firewalls, without any added security apps, and without any added anti-malware apps?

if you’ve tested that, Apple has several different macOS firewalls around just to add to the confusion.

You’ll want to try this Mac on a different network, too.

Did you ever try the advice about creating a new Location?

Failing that, go ahead and post the Etrecheck report.

Early on, I deleted all 'remembered' locations. Later, I deleted Wifi, restarted and readded wifi. If readding Wifi is adding a new location, then yes, I've done that.

I'm checking on EtreCheck now.