CAN’T SIGN INTO MESSAGES ON NEW MACBOOK PRO

When I enter my Apple ID and password into the Messages sign-in dialog box, I get an error message “Could not sign in to iMessages. An error occurred during activation. Try again.”

I’ve looked at random pages online including Apple support and Communities pages, done the suggested things but to no avail. Messages is working on my iPhone, iPad mini, and old MacBook Pro.

Any ideas?

For the premium one pays for Apple, it should not be this hard to get going on a new machine. Looks sharp, though.