dm900 login: root
login[389]: root login on 'ttyS0'
root@dm900:~# cd /tmp
root@dm900:/tmp# wget https://dreamboxupdate.com/opendreambox/...00-20190911.bin
Connecting to dreamboxupdate.com (82.149.226.170:443)
wget: server returned error: HTTP/1.1 400 Bad Request
root@dm900:/tmp#

I've downloaded "zImage-rescue-3.14-r0-dm900-20190911.bin" to my computer folder "C:"
Can I upload it to the "tmp" folder ?