Comtrend CT-536+

This device is NOT RECOMMENDED for future use with OpenWrt due to low flash/ram.
DO NOT BUY DEVICES WITH 4MB FLASH / 32MB RAM if you intend to flash an up-to-date and secure OpenWrt version onto it! See 4/32 warning for details.

1) This device does not have sufficient resources (flash and/or RAM) to provide secure and reliable operation.
This means that even setting a password or changing simple network settings might not be possible any more, rendering the device effectively useless. See OpenWrt on 4/32 devices what you can do now.

2) OpenWrt support for this device has ended in 2022.
19.07.10 was the last official build for 4/32 devices.

Comtrend CT 536+ / HG 536+ is based on a Broadcom proccessor (board ID 96348GW-11).

SoC CPU speed Ram Flash Network DSL port USB Serial JTag Buttons
Broadcom 6348 256MHz 16MiB 4MiB 4 x 1 no driver requires soldering Yes Yes One: Reset

As reported in the Attitude adjustment announcement, for 16MiB of RAM devices you should better stay with Backfire (linux 2.6.32), or you will experience contention problems due to an often lack of free memory.

The OpenWrt correct firmware is openwrt-96348GW-generic-squashfs-cfe.bin, which can be directly flashed from the original firmware page.

Notice that ''Backfire'' does not implement the failsafe boot with the reset button yet, for this router. Failsafe can be triggered only through the serial line.

A usual procedure to flash with OpenWrt using the factory CFE bootloader:

  1. Download your .bin image
  2. Set up a LAN connection with the router, your computer having the IP (on some Comtrend CT 536+ it has to be, so change to .100 if .2 doesn't work)
  3. While pressing the reset button, power on the device and keep the button for 10 seconds
  4. Once releasing the reset button, you can browse to and a web page will prompt you for a .bin firmware file. Provide the openwrt file and submit it.
  5. Wait some minutes, and OpenWrt will be ready at

This procedure will not overwrite the CFE bootloader, so you can use it later to reflash the router with any other firmware.


NOTE: Onboard DSL modem is NOT SUPPORTED

However you can connect an external modem bridged to a LAN port.

All required packages are already installed in the default image.To configure PPPoE with UCI, do this:

uci set network.wan.proto=pppoe
uci set network.wan.username=
uci set network.wan.password=
uci commit network && ifup wan


Note: if you need QoS for consistent low latency on an ADSL connection, which is a common scenario, you should consider installing the dsl-qos-queue package instead. It works much better than the Linux QoS because it does factor in the ATM overhead, which can be significant.

Install the qos-scripts package:

opkg install qos-scripts

Basic QoS configuration using UCI:

uci set qos.wan.upload=192            # Upload speed in KB
uci set         # Download speed in KB
uci commit qos

Start QoS and enable on next boot

/etc/init.d/qos start
/etc/init.d/qos enable
Architecture: MIPS
Vendor: Broadcom
bootloader: cfe
System-On-Chip: BCM6348
CPU/Speed BMIPS3300 V0.7 / 256 MHz
Flash-Chip: Macronix MX29LV320ABTC-90G
Flash size 4 MiB
RAM HY57V283220TP-7 / 16 MiB
Wireless: Broadcom 4318 rev. 9, 802.11b/g (mini-pci)
Antenna 1x
Ethernet: Broadcom BCM5325 w/ vlan support swconfig
USB possible with mod
Power adapter 16.5 V AC 850 mA / EVERGLOW adv165085
Power margin succesfully tested with a power adapter of 18 V 500 mA
Serial: Yes

Model Number

Front of the casing

Back of the casing

Note: This will void your warranty!

To open the case remove the two rubber feet on the opposite site to the antenna jack, they will reveal two crosspoint screws.

Main PCB

port.serial general information about the serial port, serial port cable, etc.

How to connect to the Serial Port of this specific device:

Use a serial TTL adapter.

port.jtag general information about the JTAG port, JTAG cable, etc.

How to connect to the JTAG Port of this specific device:

  1. you could read about bootloader in general
  1. as a beginner, you really should inform yourself about soldering in general and then obtain some practical experience!

It has to be soldered, see here:

Required materials
  • 1 x LM7805 (Voltage regulator, consider a step-down model)
  • 1 x Ceramic capacitor 0,33uF 20V
  • 1 x Ceramic capacitor 0,1uF 5V
  • 1 x Electrolytic capacitor 100uF 25V
  • 3 x Resistors 15K 0,25W
  • 1 x USB Connector
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  • Last modified: 2021/01/15 22:29
  • by danitool