Hello Victorhugo_lc,
Good day. Thank you for the question.
If you referring to having the best way to keep the GPRS connecting alive when vehicle is parked, then I suggest that you choose the sleep mode as Online Deep Sleep. It does not close the GPRS context if one was previously opened and you may set the Data Acquisition to a longer period while its parked to save more data. https://wiki.teltonika-gps.com/view/FMB120_Sleep_modes
However, in this case you have disabled the sleep mode and set the Open Link Timeout to max (259200) so there could be a chance this the connection has be closed by the server itself or due to other reason. We will need to analyze on your device logs to confirm this.
My suggestion is that you capture the device logs and share with us via VIP Helpdesk, so we can share any files/updater should you require them in future since we do not share any files on community forum. If you do not have a VIP Helpdesk account, you can check with your Distributor/Sales manger to provide you the access. If you don't have any contacts with our Sale managers, please contact with them on our official website https://teltonika-gps.com/ and click on the "Contact Us" button. When you click, please fill the form and submit it.
Note: as a topic, please choose "Vehicle telematics" or you can send an e-mail with description of your situation to info@teltonika.lt
Appreciate your kind understanding.
Best regards.