iPhone 6 will not connect to cellular 3G networks

[labradoor1]

Hello I have an 11 month old iPhone 6s Plus bought from Apple 11 months ago. It is fully up to date at IOS 11.2 etc and has suddenly stopped locating to 3G talkmobile ( Vodaphone ) signal even in strong areas. It just keeps on saying searching in the top LHS screen rather than Talkmobile 3G. Which my wife's iPhone 7 nearby, sees easily. A SIM card swap with wife's did not help and the sim was not happy in hers. A new sim was supplied and after many restarts & resets it works for a day or so before failing & goes into searching mode for the 3G signal. The new sim works in hers but only intermittently in mine. A hard reset has not cleared it. Any advice please?

 

[Sherry_B]

Welcome to iMore!

Honestly it sounds like you need to bring the phone in to your local Apple store. Give them a call to set up an appointment at the Genius Bar.

Before you take the phone in, perform a backup to iCloud over WiFi, and then factory reset the phone and set it up as new. Once they're done running tests on your phone, or replacing your phone with a new one they'll help you do a restore from your backup. The diagnostics they'll run on your phone will perform better if your phone is factory reset without any restore from backup. You'll want to get in there though before your 1 year warranty is up.

 

[labradoor1]

Thanks very much for the welcome & advice Sherry_B.

I rather feared that might be the case with it needing a Genus check out. I'll certainly do everything you suggest with the backup info and book it in, hopefully for next week. Unfortunately the phone was a replacement for a faulty screen one that failed on me & which they let me have for £140 but with only a 6 month guarantee. I've not much option but to take it in & see what they say. Thanks again..