My OpenWRT One has now arrived. The problem now, is how to replace my existing router (BT HH5/OpenWRT ver 24.10.0) with the new hardware?
Without thinking too hard, I had naively assumed that I would use the LuCI Backup function on the old router and then restore to the OpenWRT One.
Oh silly-me... If only it were that simple!!
Any suggestions on how I can go about this - without having to open both routers and go through each and every page of the LuCI interface copying one to the other?
Reading your initial post here, I think you already came to the point realizing that things aren't that easy, if the hardware changes.
I never migrated OpenWRT to another hardware platform. But I think you will have to configure your OpenWRT One manually, like your BT HH5, and replace the old router with the new one.
If it would be the same hardware, you could just use the backup and restore mechanic.
Make copies of everything in /etc/config/ from the HH5, then compare with the new corresponding files... I would guess wireless and network (and firewall) to need same manual work (so I likely would configure these from scratch on the One taking the old ones just as guidance for what effects to achieve). I would guess quite a number of these file to be viable with minimal editing (if editing is required at all) but I would still manually check each.
if you apply one change at the time, you can always roll back using the serial console, if any of the changes (firewall most likely) would lock you out.
Config backups aren't compatible between different models, depending on the details not even between two different identical models (MAC addresses).
If you are familiar with OpenWrt, you certainly can diff- and match, but there are very few files that can be copied verbatim (without careful inspection):
network
will differ, considerably
wireless
will differ, at least the device path (mix^wdiff and match might be possible here)
system
will differ in important aspects (LED definitions), but this file is easily reconfigured from scratch anyways
firewall
interface names can differ, but other than that large parts of it are device independent (so certainly grep, diff territory)
dhcp
same story about interface names here, but the block of static leases and other DNS details can be taken over (not blindly copied)
Those are the primary files you will always need, but none of them will be guaranteed to be compatible between models.
If you know the details of OpenWrt very well, you can diff- and patch (as long as you can deal with failure and are able to debug issues effectively) - if not, you will save time and headaches by starting over from scratch.
In reality, it was not too bad. I needed to do some manual tweaking (Address & Routes), but the bulk transfer was the static leases between /etc/config/dhcp.
The tool that I found really useful Kompare (a KDE utility). With this, I was able to backup both system and then unzip on my workstation, kompare the two and work from there.
