Hi everyone,I've noticed that upgrading to firmware version 5.2.6 from previous versions is not possible without performing a factory reset. This means that a direct upgrade will not work, and resetting the device is required. This is a major issue for those managing routers deployed in multiple locations. Performing a factory reset on already configured and fully functional devices is highly disruptive. It’s practically unthinkable to visit every single site just to update the firmware. Has anyone found a workaround, or is this an intentional requirement from DrayTek? Looking forward to your insights! 

Don't know if you'd seen this but the international release notes have this extra passage not included on the UK release notes (doesn't really help you though):-

Known Issue
To enhance security, firmware version 5.2.3 and the later version modified some system default values and implemented RE pattern checks and command injection checks on system parameters, fields, and values. These changes may cause configuration incompatibilities. Customers attempting to upgrade to the new firmware version may encounter issues such as the firmware version not changing after the upgrade or being unable to import previously backed-up configuration files. In such cases, we recommend that customers reset to factory default settings and reconfigure to resolve the issue.

Oh, great… that’s exactly what I needed to hear right now!I’ve got a lot of these routers spread all over Italy, and if this means I’ll have to manually reset and reconfigure them just to get the firmware update to stick, that’s a nightmare scenario. We’re talking remote sites, minimal local IT support, and now potential downtime if something goes sideways. Have they at least provided a way to check in advance whether a specific config will cause issues? Or is it just trial and error - update, hope for the best, and factory reset if it fails? Because if that’s the case, I’m going to need a very strong coffee before I even start planning this rollout...

I updated mine without issue, 5.2.6 went straight in with the normal reboot. You should not be okay I hope.

Always a joy to read posts where people skip all the useful details — like what version they upgraded from, what version they upgraded to, or which browser they used (not that I didn’t test them all, of course) — just to enjoy the thrill of telling others they're wrong. But hey, thanks for the fascinating contribution — what a delightful way to start the week with a smile!

I upgraded from 5.25 to 5.26, it does say 5.26 in the title, and since you need to update from what I understand with Draytec modems each firmware in sequence i thought that would have been obvious, sorry for my mistake (or I am wrong thinking each one has to be updated in sequence) so you can not go from say 5.1 to 5.26 as far as I was told.

The modem is a Vigor 167-K The UK version using the UK firmware and as I said I updated from 5.25 to 5.26 using the 'al'l version of the firmware. I hope this helps.