Why does phone never connect to 5G

After month 3 of using Lebara sim the phone only ever connects to 4g never see 5G. Why has this happened?

Xerjin well assuming your phone is capable of receiving 5g, some older phones aren't this is most likely because your mobile settings are not set to receive 5g, check the settings and select the 5g option when 5g is avaliable, don't set it to receive 5g only as some areas still don't have 5g coverage