Unable to download submissions on odk central

1. What is the issue? Please be detailed.
I am hosting ODK central on AWS EC2 t2 medium with 128GB volume on Ubuntu I can't download submitted data from the server. I can view, submit, and even add new forms to the server but downloading it gives me this error "Something went wrong: error code 504."

2. What steps can we take to reproduce this issue?
I tried downloading from different projects on the server and the error still keeps coming up

3. What have you tried to fix the issue?
I have tried increasing the memory using nana .env to 4 and then 6Gb but no change.

4. Upload any forms or screenshots you can share publicly below.

Any idea how to resolve this please?