Swisscom “Pirelli Centro Grande” firmware downgrade

I had a problem with the new Swisscom firmware and my VPN. Apparently to due a QoS setting it didn’t work anymore.
The only way to get the VPN working again was apparently downgrading the firmware to the previous one.
Here the steps to downgrade from Vx226x1_60202 to Vx226N1_50037_4b020

Warning: The following procedure may brick your device, do it at your own risk and only if you really know what you’re doing.

Important: if you really need to downgrade your router call the Swisscom helpdesk, their support is great and will help you.

Download the current firmware, you never know… ;-)
Download the previous firmware from:
Download the previous recovery firmware from:
Strip signature from the old firmware, otherwise it is not accepted:

$ tail -c +146 Vx226N1_50037_04b20.rmt > Vx226N1_50037_04b20-nosig.rmt

note: I think it shouldn’t matter, but first I used a different file extension than .rtm and I had a problem in a couple of downgrade attempts, until I used the .rtm extension also for the sig stripped file and everything worked well. It makes no sense to me and may be a coincidence with other factors, anyway something to bare in mind.

All the rest must be done without DSL cable plugged.

Put router in recovery mode (push and hold the reset button pushed for 30 seconds after switching the router on)
Browse to (default IP) to access the firmware recovery interface
Upload Vx226N1_50037_04b20-nosig.rmt

$ ssh admin@ (default pwd: 1234)

Enable full admin interface

OpenRG> conf set wbm/admin_wbm a25B06c81

(or enable it just one time: conf ram_set wbm/admin_on 1 )

OpenRG> system reboot

Browse to
That’s it.
If everything is and works as expected, finalize the work and downgrade also the recovery firmware.
Go to firmware upgrade and upload the old recovery firmware Vx226N1_50037R.rmt
Disable the remote management: TR-069 and TR-064.
Plug your DSL cable and the router should connect to the Internet.

As said do it at your own risk and don’t blame me if you brick your router.
If something goes wrong you can still put the router in recovery mode and upload the current firmware. I had to use this once. The hiccup is that the router sets the default password for the access, while Swisscom has stored your last set password. This is a deadlock as you’ll not be able to change your router password.

See also Downgrade von Firmware 6.x auf 5.x from Tux0ne.