siriobasic da qualche tempo non puoi più aggiornarlo "direttamente" facendo l'upload del file da browser. E' scritto sulla prima pagina delle note:
If HT8xx firmware version is equal or older than in 1.0.39.4, users cannot use web UI
option “Upload from Local Directory” to upload a firmware file equal to or newer than
1.0.41.2. Please configure web UI option “Firmware Upgrade and Provisioning” to set
a valid method for the device to obtain firmware via TFTP/HTTP/HTTPS over the
network. Please see section “Upgrading and Provisioning” in HT80X Administration
Guide, HT81X Administration Guide, and HT818 Administration Guide for details.