Internet Connection Issues

For years, I have successfully used an Airport Extreme router.

I recently moved, leaving the AE Router behind.

I have set up my internet service, using a modem / wifi router combination from the cable company. The set up is complete and I have service.

I have successfully connected my iPad, iPhone, AppleTV and two other non-apple devices to wifi. All devices can connect to the internet without issue.

My mac can see the wifi network and successfully connect. However, the system shows there is no internet connection. When I open Safari, it will open random websites like google and yahoo but not LinkedIn, my country club, Apple, etc. As a test, I took my mac to a friend's home and replicated these results.

When I shut down wifi and connect with an ethernet cable directly to the modem, the results are identical.

My guess is there is a setting(s) that is keeping the mac from connecting to the internet as it is looking for the AE router.

Any suggestions on what may be causing this or what I could do to fix it?

Thank you in advance for your help!