My new 6s has consistently no signal is there something wrong with the phone itself?

Does "no signal" mean:

• No cellular signal?
• No WiFi signal?
• Both?

Are you in a good cellular coverage area (e.g., a city)?

Do you have things obstructing your iPhone's antennas (near the horizontal stripes on the back of the iPhone)?

Is your iPhone around some electrical appliance like a microwave? Is it around some wireless car key (which would cause interference)?

Ah, thanks for clarifying.

Yes, it's not at all clear why the 6S would struggle where the 5C worked fine.

I suggest taking your iPhone to an Apple Store (make a genius bar appointment before going) or an Authorized Apple Service Center.

https://getsupport.apple.com/GetproductgroupList.action?caller=rcon