How do I update the firmware to standby partition via FTP on the USG Flex H model?

Zyxel_Jeff

Scenario :

Users typically use the Web-GUI to update the firewall firmware, but it's also possible to use FTP for firmware updates. This FAQ will guide you on how to update the firmware to standby partition via FTP on the USG Flex H model

Answer :

1)Checking whether the standby partition is on firmware 1 or firmware 2.

Log in Firewall via SSH:

usgflex50h> show version
firmware 1
model-id "USG FLEX 50H"
firmware-version V1.36(ACLO.0)
build-date "2026-04-09 08:19:19"
boot-status Running
..
firmware 2
model-id "USG FLEX 50H"
firmware-version V1.37(ACLO.0)
build-date "2026-04-09 08:19:19"
boot-status Standby

In this sample, the standby partion is on Firmware2

2)Please prepare a PC to connect to the firewall's LAN port and obtain a DHCP IP (for example, the assigned DHCP IP is 192.168.168.33 with the default gateway IP 192.168.168.1) from the firewall. Then, open the Command Prompt and access the FTP server through the default gateway IP (192.168.168.1), then upload the firmware .bin file (you can place the .bin file directly in the C:\ file path) to the firewall.

C:\Users\WindowsPCUser>ftp 192.168.168.1

Connected to 192.168.168.1.

220 FTP Server (FTP Server) [::ffff:192.168.168.1]

500 OPTS UTF8 not understood

User (192.168.168.1:(none)): admin

331 Password required for admin

Password: (please enter the password)

230 User admin logged in

ftp> bin

200 Type set to I

ftp>cd firmware2

If standby on Firmware1，cd firmware1 ; 

If standby on Firmware2，cd firmware2 ; 

ftp> put C:\138ACL0C0.bin

200 PORT command successful

150 Opening BINARY mode data connection for 138ACL0C0.bin

226-firmware verifying...

226-firmware updating...

226-Please Wait about 5 minutes!!

226-Do not poweroff or reset,

226-system will reboot automatically after finished updating.

226 Transfer complete.

ftp: 107629914 bytes sent in 2.45Seconds 43966.47Kbytes/sec.

Once the .bin file is successfully updated to the firewall, it will automatically reboot.