Hi rubel_dj,
- Please try resetting your network settings and try again. (Settings > System > Advanced > Reset options > Reset Wi-Fi, mobile & Bluetooth)
- Please tell me your mobile network provider
- Please show me a screenshot of the signal strength when the problem appears.
(Settings > System > About phone > SIM status)
- Please change to another SIM card by another network provider, and check if the problem still appears.
Please also put your SIM card into other phones and check if the problem appears.
- What kind of location does this happen? Are you in any building/ on a transportation/ in the basement/indoors or outdoors?Please check in other locations as well.
- Could you tell us your firmware version?
Settings > System > About Phone > Software information
Thank you 🙂