2012 Mac Pro losing network connectivity
Recently my 2012 Mac Pro has started losing internet connectivity. Both WiFi and Ethernet cables show valid IP address from the DCHP server, but there is not data getting through the IP stack. Turning off/on the WiFi or unplugging the ethernet cable does not help.
The only two things that help are: 1)restarting the computer, or opening Network Preferences, creating a new Location (other than Automatic), say Test, and then forcing WiFi to get a new IP address from the DCHP server. At first, it only finds some phantom IP6 address, then eventually gets a valid IP4 address. Network connectivity returns as normal. When connectivity eventually stops again, returning back to the Automatic location restores the IP data flows.
This problem occurs with either High Sierra or Mojave, which probably use the same TCP/IP software stack. The system ran fine for years and losing network connectivity just started a few months ago.
Mac Pro, macOS 10.13