Hi
s.farajollahpourThank you for your asking. Kindly provide the information below so that we can better assist you.
1. Does the issue always happen? Or does the issue appear after any system/apps' download or update?
2. Do the devices all have the difficulty to link on different Wi-Fi routers? Because sometimes the Wi-Fi or bluetooth issue are caused by the compatibility between specific router/device and the phone.
3. Please try "the Factory Reset"
Settings>System>Reset options>Erase all data(factory reset)
Please note that once the Factory Reset is completed, all data, apps, settings and personal information will be deleted.
If the situation remains the same after performing the Factory Reset, I may need you to collect logs for further checking.