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]

Yes, we have set CONFIG_DOWNLOAD_CLIENT_BUF_SIZE to 4096 and tried fragmentation size both 1024 and 2048 however the download still fails.

We have tried to setup another server and set fragmentation size to 1024 on the server side and found out that download does works for  both CONFIG_DOWNLOAD_CLIENT_HTTP_FRAG_SIZE_1024 and CONFIG_DOWNLOAD_CLIENT_HTTP_FRAG_SIZE_2048.

Unfortunately we are unable to change the fragmentation size on the AWS server. Is there any other work around we could try?