Update zyxel USG FLEX 100 (4.55 to 5.21)

Wassim Posts: 1
edited April 8 in Security
Hello everyone,

I have a zyxel USG FLEX 100 and I need to update it. However, it is in version 4.55 and I would like to upgrade it to 5.21. Normally, I would have to go through intermediate versions but these are not available since the ftp has been closed.

Do you have a link to get the old versions of this firmware or should I update directly to 5.21? In the last case, I would have to do a reset and then restore my configuration?

Best Answers

  • PeterUK
    PeterUK Posts: 1,498
    50 Answers 1000 Comments Friend Collector Fifth Anniversary
     Guru Member
    Answer ✓
    You can get 5.10(ABUH.0)C0 here 
    Download Library | ZyXEL

    backup your config and try upgrading  
  • mMontana
    mMontana Posts: 995
    25 Answers 500 Comments Friend Collector Third Anniversary
     Guru Member
    Answer ✓
    I stand by @peteruk suggestion of backing up configuration.
    Which means outside the device, at least 1 copy.
    If something goes wrong, back to defaults then apply.
  • Zyxel_Emily
    Zyxel_Emily Posts: 961
    Zyxel Certified Network Administrator - Security Zyxel Certified Sales Associate 100 Answers 500 Comments
     Guru Member
    Answer ✓
    You can upgrade USG FLEX 100 from 4.55 to 5.21 directly. Before upgrading, remember to back up startup-config.conf of firmware 4.55. Then upload firmware 5.21 to standby firmware partition. More details can be found in this discussion

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