Can't download files greater then ~1,5gb

Hi, in german thread i get not so much response, therefore i try it here.

I can upload files to my seafile server with sizes greater then 1,5gb. This works without problems.
But i can’t the files download again.
I’ve tested it with several files:

With 300mb file, the download begins after ~4,5 seconds
With 600mb file, the download begins after ~9 seconds
With 1200mb file, the download begins after ~18 seconds

With 3000mb file, i get a error 500 after ~25 seconds

The strange thing is also i get no hint in the logfiles…
My installation runs on Ubuntu 18.04 LTS with nginx

Have anyone a similar problem and know what can i do to solve this problem?

Many thanks for your help!

You call this lengthy thread no response?

The problem is solved. There was a problem of our sophos firewall. @rdb gave the hint.

Thanks