To verify that you didn't bring over any gruf from the old notebook, try creating a new user account on your new MBP. Log out of your existing account, and then, log in with the new account. Does the notebook connect to the Wi-Fi automatically now?
If not, then try the following steps. If any step resolves the problem; stop, do not continue with the next:
Step 1
- In Finder, go to /Macintosh HD/Library/Preferences/SystemConfiguration
- Move (not copy) the preferences.plist file to the macOS desktop.
- Restart the computer.
- Verify that the issue is resolved. If not, go to the next step.
Step 2
- In Finder, go to /Macintosh HD/Library/Preferences/SystemConfiguration
- Move (not copy) the NetworkInterfaces.plist & com.apple.airport.preferences.plist files to the macOS desktop.
- Restart the computer.
- Verify that the issue is resolved. If not , go to the next step.
Step 3
- In Finder, go to /Macintosh HD/Library/Preferences/SystemConfiguration
- Move (not copy) the entire SystemConfiguration folder to the macOS Desktop.
- Restart the computer.
- Verify that issue is resolved.
Please post back your results.