Stop my 2 iphones from ringing for each other

You said you tried turning off allow calls on other devices. Did that solve the problem with the other phone, ignoring the laptop inconvenience?

If you want calls on the laptop it will be difficult to stop calls on the other phone.

Stopping unknown callers is notorious for missing important calls. Spam calls are a plague that can't be stopped easily. Having some quiet time using Focus accepting only contacts is an option.

When you allow calls on other devices, can you not select the device in question? You should be able to turn off the other iPhone so that calls do not go there.

@stupidoldperson

That setting should do it, but I have mine turned off completely.

I did ask if it solves it if you turn it off completely.

Go to Settings, Your name, iCloud and turn off anything you don't want to share across all devices, like messages maybe.

Did you swap SIMS when you got the new phone?

In Settings, Phone, is 'My Number' correct?

Settings, Messages, does each phone have just one number for messages?

There seems to be a crossover somewhere.

Not a problem. I just know the OP wanted to be able to handle calls on the laptop, so they just had to turn off the phone they did not want calls on, but still keep calls on other devices turned on. Take care.

Settings, General, Soft ware update

It will not be pushed as you have a choice (for the first time ever) to stay on 14.8 or upgrade to 15

sorry I'm talking to the wrong person Chris!

I still am!

"...iphone #2's number was ported from my vintage landline, ..."

That's outside of my experience, but good luck with the trials.