Firmware Upgrade Bugs before v4.0.4 (EG4xxx)
Certain firmware versions prior to 4.0.4 have problems with firmware file uploads. On EG4xxx (Core/Pro), if firmware upload fails prior to v4.0.4, install v4.0.1 followed by v4.0.4:
1) Install v4.0.1 via file: download
2) If successful, install v4.0.4 via file upload: download
Newer firmware versions can be installed normally via online-connected download or manual file upload (latest versions available via eGuard).