Messages app is not connecting on my MacBook Pro laptop OSX 11.6.8 but does on the old one OSX 10.11.6

Messages app not connecting on MacBook Pro laptop OSX 11.6.8, but does on old one OSX 10.11.6. Why?

I saw a post with the following steps to take:

After trying each step below, try to send a message again. 

• Restart your Mac. Choose Apple menu  > Restart, then click Restart. 
• Make sure that your software is up to date. Learn how to update the software on your Mac.
• Make sure that your Mac is connected to the Internet. To check your Internet connection, try loading a page in Safari or another web browser.
• Check that the date and time is set correctly on your Mac.
• Make sure that you enter the correct phone number or email address for the contact.

ALL of those situations are NOT an issue. What else is there and why hasn't this issue been resolved by now? My newest laptop came out in 2013. A fix surely should have happened by now, so where's the patch? My laptop software is all up to date.