We have been testing your Gateway with the modbus to lora converter RA7431,
we noticed that when internet is removed from the gateway, The uplinks from the RAK7431 get dropped, and only after reestablishing the internet to the gateway and waiting for several minutes the uplinks carry on, leaving all the data dropped in between seems to be lost forever.
We are wondering if there is a hidden functionality in the gateway that uses the TF memory card to store all than information and once the internet connection gets reestablished the data stored in the Memory card can be send to AWS as the consecutive uplinks.
Fig1. Rak7431 Uplinks get dropped when there is no internet connection in the Gateway