Go to Settings > Network & internet > SIMs > APN
If the correct APN is selected and its entries are correct you can delete it and add it again , or delete it and reboot the phone, or reset the mobile network settings, search the settings for this.
Go to Settings > Network & internet > SIMs > APN
If the correct APN is selected and its entries are correct you can delete it and add it again , or delete it and reboot the phone, or reset the mobile network settings, search the settings for this.