Der folgende Blogeintrag bezieht sich auf folgenden Wiki-Eintrag¹⁾. Damit habe ich erfolgreich openwrt auf einen Edgerouter X geflasht.

wget https://downloads.opennet-initiative.de/ubnt/edgeos/openwrt-ramips-mt7621-ubnt-erx-initramfs-factory.tar
scp openwrt-ramips-mt7621-ubnt-erx-initramfs-factory.tar ubnt@192.168.1.1:/tmp
ssh ubnt@192.168.1.1  [ PW = ubnt ]
cd /tmp
add system image openwrt-ramips-mt7621-ubnt-erx-initramfs-factory.tar
  Checking upgrade image...Done
  Preparing to upgrade...Done
  Copying upgrade image.../usr/bin/ubnt-upgrade: line 509: [: too many arguments
  Done
  Removing old image...Done
  Checking upgrade image...Done
  Copying config data...Done
  Finishing upgrade...Done
  Upgrade completed
show system image
  The system currently has the following image(s) installed:
  ramips r5484-69d22a6 SNAPSHOT (default boot) 
  v1.7.1.4821926.151103.1114 (running image) 
  A reboot is needed to boot default image
reboot 
  Proceed with reboot? [confirm][y]
  Broadcast message from root@ubnt (pts/1) (Thu Jan  1 01:10:25 2015):
  The system is going down for reboot NOW!

Danach das aktuelle openwrt fuer den erx herunterladen ²⁾. Und auf den Router flashen.

scp openwrt-19.07.3-ramips-mt7621-ubnt-erx-squashfs-sysupgrade.bin root@192.168.1.1:/tmp

root@OpenWrt:~# cd /tmp
root@OpenWrt:/tmp# sysupgrade openwrt-19.07.3-ramips-mt7621-ubnt-erx-squashfs-sy
supgrade.bin 
Cannot save config while running from ramdisk.
killall: watchdog: no process killed
Commencing upgrade. All shell sessions will be closed now.
Connection to 192.168.1.1 closed by remote host.
Connection to 192.168.1.1 closed.

Nach dem reboot ist die aktuelle Version von openwrt installiert.