rsync freezing/hanging/stopping after a couple of files

I have this folder with 25,000 images (around 80MB total) and I want to transfer all of them to a server.

This is the command I am using:

rsync -av -e 'ssh' ./pics/ user@132.456.789.10:~/pics/

The transfer freezes after a couple of files and when I stop the process, I get this error:

rsync error: received SIGINT, SIGTERM, or SIGHUP (code 20) at rsync.c(644) [sender=3.1.2]

I know that it doesn't work because the server location doesn't have the images after freezing.

I tried running the command without the console output -v, but it still freezes.

What might be the problem?