No mobile data connection after Oreo update

[noiro]

Hi, 

I updated to Android 8.0. two days ago and since then, I have managed to connect to the internet only through WiFi. I live in a 4G area so coverage is not an issue. The signal bars show as full and H+ but I recieve tunnel errors when trying to load a website, a general connection error when trying to listen to an audiobook/Spotify and my messages won't go through on Whatsapp and Facebook messenger. I've tried rebooting the device, switching WiFi and airplane mode on and off with out effect.

[Kke]

After upgrading to 34.4.a. 2.19 no phone calls or 4g, just wifi. 

[Uliwooly]

@Kke @noiro

what if you repair the phone with XC once more?

[Sg2018]

Did you get it to work? Same issue 

[Kke]

Nope. Just wifi, using substitute phone

[Strampke]

What if you Download settings for internet and MMS once more?

[Kke]

The problem is that sim card is not being read, I can't even make phone calls. I somehow need to get android 7 back o the Oreo version ending .364. 

[Strampke]

Usual testing:

Put SIM in another phone and test.

Did you put the SIM correct in your phone.

Same problem with another SIM in your phone?

Does it happen in safe mode too?

[Sg2018]

Mine also will not work for nearly 2-3 weeks tried all these steps and more having to send it for repair tomorrow but I don't know if I'm confident they will fix it or it will just happen again 

[Kke]

The Sim is OK, I'm using it on another phone. Tried in safe mode too. To no avail. The story is simple. I upgraded first to oreo version ending. 364, than, next day, received message to upgrade to version ending. 19.after I upgraded to that version, after restart,  the same moment the Sim stopped working.