Galaxy S23 - Once mobile signal lost doesn't rejoin

[Cryoman]

Hi everybody, this is a wierd one.

First some background. I'm in the UK, Carrier is ASDA Mobile who use Three/Vodafone network. Signal herabouts (just south of Croydon) is pretty good almost everywhere.

I have a new (to me at least, bought as open box from EBay) Galaxy S23.

Everything is working fine except mobile signal in the car. 

There's a notorious "not spot" under a bridge in Chpstead Valley Road near me. The signal on my car's handsfree disappears completely. I am unable to make calls, access my contacts or look at recent calls.

With my old Xiaomi Mi11 Lite 5G the signal returns after about 1 mile but with my new S23 it doesn't return. Ever.

The only way I can get it back is by stopping, taking the phone out of my pocket and pressing the power button to wake up the screen. When I do this the signal returns full strength immediately.

As luck would have it I have just changed my car and I can confirm this happens on both the old car and the new one so it is definitely an issue with the phone, not the handsfree or Bluetooth.

So I'm thinking there is a setting somewhere but all looks to be in order. I have factory reset the phone several times but the issue persists.

Has anybody else heard of this? I'm really disappointed as the S Series is their top line and whilst it is not a new phone per se it is fresh out of the box as it were.

Any advice would be appreciated

[Tourbillon De La Vie]

Is the phone in power save mode?

[Cryoman]

Hi and thanks for trying to assist. Nope. All normal, with battery levels good. I'm wondering if the new "Extend Lock" feature might have something to do with it but I don't see how a locked phone would stop it accessing Bluetooth paired devices?

[Piper123]

Go to settings and:

Reset MOBILE network settings

You won't lose data and your network will update APNs almost immediately.

[Cryoman]

Hi Piper123 and thanks for taking the time to respond. I tried resetting the network settings but sadly this didn't solve the problem. 

I did a bit more troubleshooting over the weekend and I believe the issue is with the Bluetooth.

Having reset the network settings I visited the local "not spot" again, and as usual as I drive under the bridge the signal icon became greyed out on the car Handsfree display as usual.

So I stopped, took the phone out of my pocket and held it next to the car display unit and the signal returned almost immediately.

So I drove back to the "good" side of the bridge and rather than putting the phone back in my pocket I left it on the centre console. This time driving under the bridge the antenna/signal strength icon didn't even disappear so I'm thinking bluetooth? But I'm guessing that'll be a repair job, not a fix that I can do?