Thank you!! Exactly this was the problem! If I could like your post 1000 times I would.
Here's the full answer, I changed all of the config files appropriately (ccnet.conf, seahub_settings.py, etc).
But, I did not change the same settings in the web interface, where SERVICE_URL and
FILE_SERVER_ROOT pointed to the old server address.
From the Seahub_settings.py doc:
" The config items are saved in database table (seahub-db/constance_config). They have a higher priority over the items in config files."
So in short, must change both the config files AND web settings (or disable web settings).
Just in case anyone in the future makes the same dumb mistake...