mynew iphone SE 2 has poor wifi range,why:

What band are you connecting to on each phone? 2.4 GHz or 5 GHz? The 5 GHz band is faster, but has less range and doesn’t penetrate walls as well.

If there is a very large difference (e.g., the SE2 has a range of 10 feet and the 6 100 feet) then there’s probably a hardware issue in the SE. You can try standard troubleshooting:

• Restart your router
• Forget the network on the phone, then reconnect
• Settings/General/Reset - Reset Network Settings

If none of that helps use the Contact Support link at the top of this page to discuss repair options.

That sounds more like a problem with your phone. Contact Apple about having it evaluated. Does it happen on all networks, or just your home network? Both 20 feet and 50 feet sound abnormally low; even 5 GHz Wi-Fi should easily have 150 feet with no obstructions, 2.4 GHz even more.

If you have a large space replacing the router with a mesh network is a better solution than a range extender.