Please try the below:
1. If you are in a place with poor signal such as a closed environment like a high-speed train, the network is generally poor, and the internet will be slow.
2. If a metal protective case is used, the network signal will be affected. we recommend you remove the metal protective case or use a plastic or leather protective case.
3. Replace the SIM card to see if it works better.
4. Some operators may have set restrictions on data usage. If it exceeds a certain amount, the carrier will limit the network speed. For details, please consult the network carrier.