nRF9161 FOTA + TLS Download Error

[OhmMyGod]

Hi,

We are using `fota_download` library on our nRF9161 design running mfw-nrf91x1_2.0.1 to download a firmware upgrade image from our Amazon AWS server location.

When trying to download with TLS enabled, fota_donwload_start function errors out with errno 122: EMSGSIZE, however everything works fine when TLS is not being used. We are also able to download the image if TLS is setup on our local PC/server.

Our current understanding is that the nRF9161 delegates TLS/socket processing to the modem firmware. Adjusting the fragment size in our firmware to a smaller value hasn't resolved the problem, and error 122 persists.
We’ve looked into modifying the TLS settings on AWS server, however that doesn’t seem to be an option as of now.

Wondering if you have any recommendations on how to work around the problem?

[OhmMyGod]

Hi,

We tried a file that is 26kB in length and it failed. We also tried file that is 164 byte long and were able to download it so most likely we are running into the TLS limitation.

What are options to work around the TLS limitation ? 

We used fota_download library as is without modifications and integrated it into our project. We will not be able to use the delta update as we have other files that must be downloaded in full.

Thank you