I bought the GL-MT6000 yesterday from Amazon to upgrade my old Archer C2600.
I immediately flashed the openwrt sysupgrade and everything was going well. I even installed the packages using opkg.
When things went bad is when I backed up the settings from the archer to a tar.gz file and then I tried to restore it in the Flint 2 using the command tar -xzvf /tmp/backup-*.tar.gz -C / then rebooted.
After that, I was never able to access the router again.
No wifi network is shown, and when I connect the LAN cable there is no IP. I even ran wireshark to see what's going on and there are just no replies to DHCP requests. I even tried static addresses but still no connectivity.
I did the reset process with LAN but still no IP. Any way to recover or is it permanently bricked?
That's recoverable. It's just the network or other device config from the archer device which fucks up boot. Follow the factory reset instructions on the wiki.
Also, this is a good moment to point out the selective restore I made, which ... needs some changes in openwrt.
Restoring some config files from other devices is a no-no if you want to avoid this.
How to recover has been brought up already, so I'm just commenting on this - that cannot work, ever, at all. Don't even think about that (or similar) approach(es).
Here's a way to determine your setting and package customizations on the old router, to assist you as you manually port them over to your new router.
Summary
Backup your Archer C2600's configuration.
Make note of your existing UCI settings and your installed package list.
Temporarily reset your Archer C2600 to its defaults and repeat the previous step.
Restore your configuration from backup.
Use the diff command to compare the customized settings and packages to their default counterparts, so you can be reminded of everything you've changed from the default on your Archer C2600. Look it over to see what's noteworthy, and now you should have a listing of what settings and packages you'll probably also want to change on the Flint 2.
More detailed version
Make a new folder somewhere on your computer, such as your Desktop folder. Name it something like "OpenWrt."
Make two folders inside that folder: one called Archer C2600, and the other called Flint 2.
Inside both of those router folders, make a folder called "Settings" and another folder called "Packages."
Backup your Archer C2600's configuration for safekeeping and easy restore. Put it in ~/Desktop/OpenWrt/Archer C2600/Settings.
SSH into the old router.
Run the first command: uci show. This will show your entire OpenWrt configuration, including settings you changed but also ones you left as default. Copy & paste the output into a plain text file, and save it as ~/Desktop/OpenWrt/Archer C2600/Settings/Customized.txt.
Run the second command: opkg list-installed. This will show all of your currently installed packages, including default packages, packages you added manually, and dependencies.
When you're ready, temporarily reset your router to its default state on OpenWrt.
Repeat steps 3-5, but this time to capture what the default settings and packages are for OpenWrt on that particular model and OpenWrt version. This time, name the two files "Defaults.txt."
Now that you have the information about the defaults, restore your Archer C2600's from the backup file.
Remove version numbers from both package lists. An easy way to do that is to paste a list into a LibreOffice spreadsheet (Edit → Paste Special → Paste Unformatted Text) using tabs as the delimiter, select the column with the package names, copy it, and replace the existing contents of your package list file. Do that for both package list files.
Use the diff command to compare your customized settings to the default settings, and then separately do the same for your packages. For packages, don't worry about dependencies. Focus only on the packages you manually chose to install that were not installed by default, and make note of that.
As you set up the Flint 2, refer to your notes you now have regarding the Archer C2600. You should be able to quickly replicate your changes.
If you need help with how to use the diff command, read its manual (man diff on your computer if you use Linux or Mac), or Google it. Online diff checkers are available, but I wouldn't recommend using them for your OpenWrt settings, since those often contain sensitive information such as passwords. If you prefer a graphical tool, there are developer oriented text editors that can do it, though you may need to install diff (or a similar text comparison tool) as some kind of plug-in for that text editor, if it's not included out of the box.
It's a bit of a shame it's not more obvious that "direct" cross-device config import is not conducive to a working router. But my selective restore linked above is a workaround for those who know better.
Most except for network and wireless are safe, I think. Importing those files requires a bit of manual surgery which isn't available during a typical restore. Omitting those files is safe, but puts the user further away from where they'd hoped to be, but at least they will have something working and not "soft bricked".
@hnyman would you be able to merge the sysupgrade change to enable this feature?
