Firmware Update Tool available for LTE Extension Board
Sony just released a new firmware update tool.
It works to update the firmware on the LTE extension board from version RK_03_00_00_00_04121_001 to the most recent version RK_03_00_00_22_13151_002.
If you are experiencing any connection issues with the LTE board, please update the firmware and check again before posting your question on the forum.
Here you can find the Update Tool along with instructions on how to use it: https://developer.sony.com/develop/spresense/downloads/lte_downloads/lte_fwuptool-2/
To find out the version of the firmware on your extension board, you can run the Arduino Example LteTestModem.