Connecting Apple watch 6 to iPhone 7 Plus

Hi, I have iPhone 7 plus with the most updated system version 15.7.9 .

The phone indicated that this is the most updated version and don't give me any option to update it.

I have just received a new Apple watch (replace by the lab) - 6/44mm.

When trying to connect it to the phone, after identification process etc., I see it working but after a short time with no success, I see it makes a disconnection process.

When clicking on the "information" I get the message that I need version 17 , but as mentioned, I can't update to.

I asked the lab, and they told me they can't lower the new watch version.

Any suggestions ?