Or just use ipv6!

You could also upload directly to the filesystem and then run occ files:scan, or if the storage is mounted as external it just works.

Another method is to set your machines /etc/hosts (or equivalent) to the local IP of the instance (if the device is only on lan you can keep it, otherwise remove it after the large transfer).

Now your rounter should not send traffic to itself away, just loop it internally so it never has to go over your isps connection - so running over lan only helps if your switch is faster than your router..