If not check if your SIM card is 4G [https://www.quora.com/How-do-I-know-if-my-sim-is-4G|compatible]
+
If not check if your SIM card is 4G [https://www.quora.com/How-do-I-know-if-my-sim-is-4G|compatible] . If your SIM card is not 4G compatible, contact your service provider about getting a replacement SIM card.
If your SIM card is 4G compatible have you checked that the Network mode setting is set to LTE (or 4G) (go to ''Settings > Networks > More > Mobile Networks > Network Mode'') and have you enabled Mobile data (go to ''Settings > Networks > More > Mobile networks > Mobile data'')?
Hi,
Has it worked OK on 4G before?
If not check if your SIM card is 4G [https://www.quora.com/How-do-I-know-if-my-sim-is-4G|compatible]
If your SIM card is 4G compatible have you checked that the Network mode setting is set to LTE (or 4G) (go to ''Settings > Networks > More > Mobile Networks > Network Mode'') and have you enabled Mobile data (go to ''Settings > Networks > More > Mobile networks > Mobile data'')?