What does "connect to it through the net"? There is a place to upload it via the firmware update menu. Are you saying there is a way to grab it off the internet?
You first download the firmware onto your local system and then tell the browser to upload to the Avalon
For example you download the image from
http://ck.kolivas.org/apps/cgminer/avalon/20130624/openwrt-ar71xx-generic-tl-wr703n-v1-squashfs-factory.binand then you browse to
System -> Backup / Flash Firmware
Click on Browse, select the image you just downloaded from you Downloads an click on Flash Image
Then Ack the hash (if you want to check) and reflash the machine. Wait 3 minutes and log back in, running the new image.
By the way, are *you* the guy selling the ASIC managed hosting?
I'm offering to do managed hosting of 1 unit Avalon with 3 hashing units for EUR 100 / month in Belgium eh... never mind... why do I even bother to bring this up...
At least I've been reflashing embedded devices for the last 19 years.... it's really not that difficult if even I can pull it off...