H820-RT5350-v3.2.x Firmware Downloads

This page contains firmware levels for the older H820 4G router hardware version (Pre January 2023). This model can be easily identified physically as they have 1x WIFI connector only. This model cannot be upgraded to newer firmware series.

The newer H820 4G routers after January 2023 use the later firmware series H820-7628_v3.3.xx and also have updated hardware, they are physically identifiable by their 2x WIFI connectors. For this firmware series follow this link to the relevant page.

Applicable Part number:

H820t-W

(Pre January 2023) = Firmware H820-RT5350-v3.2.xxx = Physical difference (1x WIFI connector)

(Post January 2023) = Firmware H820-7628_v3.3.xx = Physical difference (2x WIFI connector)

(The part number is found on the underside label of the router).

Changelog

H820-RT5350-v3.2.368 – March 2026

GPS TCP server can send DIO commands to set or get DIOs.
Added MQTT with modbus.
Updated dropbear from 2019.78 to 2022.82
Fixed issue which caused SNMPv3 to not work when the configuration was changed.

H820-RT3550-v3.2.366 – January 2026

Fixed bug with accessing WEBUI on HTTPS introduced on 3.2.359.

H820-RT3550-v3.2.359 – November 2025

In development, download removed due to bug found with accessing WEBUI on HTTPS.

Added band lock for SLM770A.
Removed service port map which uses port 111.
Removed HTTP access, enforcing HTTPS access only, for EU RED Compliance.
Removed options for HTTPS weaker encryption suite, for EU RED Compliance.
Using SHA256+HMAC for firmware safe upgrade.

H820-RT3550-v3.2.355 – September 2025

Unified User Passwords
The WebUI user admin and CLI user router (root) now share the same password. Changing the admin password on first login will automatically update the CLI password.
Password Policy Enforcement
Implemented a minimum password strength requirement:
- At least 8 characters
- Must include one digit (0–9), one uppercase letter, one lowercase letter, and one special character
New Authentication Log
Added an Auth Log page under Status > Event Log > Auth Log.
- Records all login attempts (successful and failed) to the WebUI (HTTP/HTTPS) and CLI (SSH)
- Tracks failed attempts and logs lockout events when thresholds are reached
Security Page Enhancements
Updated the Network > Firewall > Security page:
- Redesigned layout and descriptions for clarity, removed ‘basic settings’ section and changed the sections to be specific to each protocol.
- IP Whitelisting moved to the top of the page
  - Whitelist now applies globally across all protocols
  - Port forwarding rules will only work for IPs listed in the whitelist
  - Whitelist rules are now handled internally (no longer added to Traffic Rules)
- Protocol Management Changes
- TELNET disabled by default and removed from WebUI management
- Removed per-protocol whitelisting for SSH, HTTPS, and HTTP
  - All protocol access is now controlled via the unified IP Whitelist
  - For per-protocol control, use Traffic Rules in the firewall
- Brute Force Protection Renamed
  The IP lockout feature for administrative protocols (SSH, HTTPS, HTTP) is now called WAN Brute Force Protection.
Fixed issue where FG132 shows the wrong band.

H820-RT3550-v3.2.354 – June 2025

Added check for HTTPS cert and key files, if it was generated by old method, it they are regenerated.
Updated HTTPS certificate generation method.

H820-RT3550-v3.2.352 – May 2025

SLM750 IP passthrough can be done on a configured MAC address, added option for Bridge MAC address on web page Network–>Mobile.

H820-RT3550-v3.2.351 – April 2025

Fixed captive portal issue.
Optimized dial process.

H820-RT3550-v3.2.350 – March 2025

Fixed issue that SLM750 disconnects internet access every 21 hours when SMS enabled.
Fixed the issue of export IPSEC log.

H820-RT3550-v3.2.349 – March 2025

Optimisation of DTU.

H820-RT3550-v3.2.347 – February 2025

Fix issue with dio_control application.

H820-RT3550-v3.2.346 – February 2025

Fixed gobinet driver conflict issue. Which impacted Sierra Wireless module.

H820-RT3550-v3.2.342 – October 2024

Updated HTTPS cert files generation method.
Added option to enable saving system log and kernel log during reboot.

H820-RT3550-v3.2.341 – September 2024

Updated DTU.

H820-RT3550-v3.2.339 – August 2024

Fixed issue that prevented static routes from being deleted.

H820-RT3550-v3.2.337 – July 2024

Added Modbus support GPS coordinate and modem signal strength.
Fixed DTU issue.

H820-RT3550-v3.2.335 – June 2024

Removed UI file browser page.
Fixed several vulnerabilities of UI.
Added NTRIP support on GPS.

H820-RT3550-v3.2.334 – May 2024

Updated password generation algorithm.
Updated NTRIP client.

H820-RT3550-v3.2.332 – April 2024

Fixed issue that caused login page error occasionally.

H820-RT5350-v3.2.326 – March 2024

Fixed an issue that cased the modem to not dial after bootup occasionally.
Update RMS.

H820-RT5350-v3.2.323– January 2024

Save config files in flash as backup automatically.
If config via UCI command or edit files in SSH, it requires to run command “save_flash”.
Removed Flash Backup and Restore at page System–>Back / Restore.
Force to change password, new password can be same as default.

H820-RT5350-v3.2.314– September 2023