Problem with ppp0

hi guys, i’ve 2 problem:
A…. I’m using raspberry cm4 and Pi4 (kali linux S.O.) with sixfab base with eg25-g quectel module. Raspberry pi4 er Cm4 and EG25-G communicate via uart serial port (rx and TX) The connection is fine and everything works fine when i use ssh. When i open another process (for example browser firefox or google )connectivity is very slow ( 9700 ms) and sometimes the module gets stuck.
Can you help me solve the problem?

B…. I would like to send a text message to the EG25-G module and be able to turn the Raspberry on and off, to date I have not found any solution. Can you help me on this?

Thanks a lot."

Best reguards Robert