iPhone Air poor connectivity everywhere, whether on WiFi or Cellular.

You won't know if you have a defective phone until you can make an appointment at the Apple Store / Genius Bar or take the phone to an authorized Apple service shop so they can run some diagnostics on the phone.

You can find a list of authorized shops in your area using this link:

Find Locations

• This is Apple's first model that completely abandons Qualcomm baseband and is equipped with a self-developed C1X 5G modem. Although the official propaganda says that the daily delay performance is better than that of the previous generation of Qualcomm baseband models, it is still in the mass production stage of the first generation, and there are many hidden dangers in hardware stability. Due to the direct failure of baseband hardware, there are a small number of user feedback cases around the world.。

If it is more serious……You can go to the Genius Bar

There will be a range of sensitivities across iPhones and it sounds like you might just be unlucky in having one that's slightly deaf but still in spec. If Apple say there's nothing wrong with it then there's not much you can do.

If you're using a case then try it without to see if it makes a difference.

If you are using a VPN then try disabling it or, better, removing it from your device completely to see if that helps.

Also you need to remember that download speed doesn't just depend on the number of bars of 5g. It also depends on how many people are connected to the cell and using it. You could be showing 5 bars of 5g but if everyone in the area is also connected and, say, streaming movie clips, then downloads could be slow because they are ultimately limited by the data rate to the cell tower (backhaul).

That won’t do anything. Those people always test it and say it’s working fine