MikroTik RB760iGS (hEX S)

Follow MikroTik Common Procedures to install the OpenWrt firmware.

Warning: use openwrt-23.05.0-rc3 for the first step of the TFTP installation, as the other RCs and the final 23.05.0 version cannot be netbooted due to too high entry point addresses:

$ for file in *760igs*; do echo $file; readelf -h $file | grep Entry; done
openwrt-22.03.5-ramips-mt7621-mikrotik_routerboard-760igs-initramfs-kernel.bin
  Entry point address:               0x80b71000 <-- netbootable
openwrt-23.05.0-rc1-ramips-mt7621-mikrotik_routerboard-760igs-initramfs-kernel.bin
  Entry point address:               0x80b91000
openwrt-23.05.0-rc2-ramips-mt7621-mikrotik_routerboard-760igs-initramfs-kernel.bin
  Entry point address:               0x80b91000
openwrt-23.05.0-rc3-ramips-mt7621-mikrotik_routerboard-760igs-initramfs-kernel.bin
  Entry point address:               0x80b81000 <-- netbootable
openwrt-23.05.0-rc4-ramips-mt7621-mikrotik_routerboard-760igs-initramfs-kernel.bin
  Entry point address:               0x80b91000
openwrt-23.05.0-ramips-mt7621-mikrotik_routerboard-760igs-initramfs-kernel.bin
  Entry point address:               0x80b91000
openwrt-23.05.1-ramips-mt7621-mikrotik_routerboard-760igs-initramfs-kernel.bin
  Entry point address:               0x80b91000
openwrt-23.05.2-ramips-mt7621-mikrotik_routerboard-760igs-initramfs-kernel.bin
  Entry point address:               0x80b91000

Discussion: https://github.com/openwrt/openwrt/issues/13255#issuecomment-1772098866, https://forum.openwrt.org/t/mikrotik-hex-s-rb760igs-cant-boot-via-tftp/175012.

Warning: Don't upgrade RouterOS packages & bootloader to 7.2.1 otherwise 'sysupgrade image' install will fail!

(downgrade to 6.46.4 verified ok) (downgrade to 6.48.6 verified ok)

Quick guide:

1. Setup TFTP server to serve intramfs image.
2. Plug Ethernet cable into WAN port.
3. Unplug power, hold reset button and plug power in.
   1. Wait (~25 seconds) for beep and then release reset button.
   2. The SFP LED will be lit in RouterBoot, but will not be lit in OpenWRT.
4. Wait for a minute. Router should be running OpenWrt. Check by plugging in to port 2-5 and going to 192.168.1.1.
5. Flash the sysupgrade.bin image with web interface or sysupgrade.

21.02: LAN1 is labelled “WAN” and has WAN firewall zone assigned by default. LAN2-5 are in LAN bridge. SFP port is unassigned.
Snapshot (as of 2021-12-27): LAN1 is in br-wan bridge together with SFP.

MAC addresses:

• The first address (E01 on the sticker) is used for WAN (ether1 in ROS).
• The next address is used for br-lan.
• The last address (E06 on the sticker) is used for SFP.

RB760iGS supports passive 24V PoE output on port 5 (marked as “PoE out”) and PoE passthrough.

If the device is powered via PoE input on port 1, the input voltage will be passed through to port 5. This can be used to chain power RB760 and a 48V-only AP by providing 48V to the router on port 1.

In any case, PoE output must be enabled with UCI:

uci set system.poe_passthrough.value=1
uci commit

This will enable PoE on boot.

Fiber SFP is broken in 21.02. This patch in master fixes it, but it is not backported to 21.02, so you have to use snapshot builds if you use fiber SFP modules. Copper modules should work in 21.02.