iPhone will not connect to wifi and if it does cuts out

Should be this case, you already tried all the troubleshooting steps (except trying to connect to a different wifi network). If the issue persists, also with different wifi networks, your 11 could have a hardware issue (battery? antenna? other internal component?) failure but we, just users like you, cannot diagnose that issue remotely, sorry.

I suggest that you contact Apple Support directly using this link:--> Contact Apple for support and service or make an appointment (*) and have your device inspected at an Apple Store or AASP (Apple Authorized Service Provider) among this list:--> https://locate.apple.com/choose-country-region . After checking it out, they'll give you all the available options.

Regards

Giulio

(*) You can do it:

• Online:--> Genius Bar Reservation and Apple Support Options - Apple;
• Contacting a local Apple Store or AASP among the list provided above;
• Using the "Apple Store" app, available and downloadable from AppStore.

On what iPhone model? Which iOS version is currently running on it?

Do wifi connection problems happen at home only, or with all wifi networks too?

Please check and let us know the answers.

Thanks and regards

Giulio

Okay, thanks, but you didn't answer to my question regarding your connection to a different wifi network (not at home).

Also, when you say "rebooted", are you talking about your modem router?

My pleasure