Can't update GXP1625 devices suddenly


Since GXP1625 devices don’t give you the option to upload the firmware directly i always used a local HTTP file server to load the new firmware.
It used to work without problems in the past but now all my GXP1625 devices inside “Upgrade and Provisioning” menu, have these settings:

and devices deny to save my new settings that link to HTTP server:

After applying the new settings and rebooting, they always come back with the old settings. It drives me mad. The PBX i use is a UCM6204.

Anyone has any idea why GXP1625 can’t save my changes?
Or is there any alternative to upload new firmware?