Thank you for the question.
According to your description, the device is sending records when it is in movement and take more time to send when it is stopped.
This behavior reflects what is configured in the Data Acquisition Mode. Where you can adjust the records generation and send periods according to what you want using the Configurator. To do this open the Configurator, go to Advanced Configuration > Data Acquisition Modes > On Stop and change the values according your needs.
As reference, you can check the Data Acquisition Mode Wiki section here: https://wiki.teltonika-gps.com/view/FMA120_Data_acquisition_mode_settings
Please let me know if it helped.