Recover Belkin RT3200

[hnyman]

@diagpope

As I understand, the device has two images to boot from. Is it deterministic which one it boots from upon reset or power cycle? Is it always a specific one, when does it change?

No, it is not a dual-boot device with two alternative firmwares (like e.g. some Linksys routers).
Instead, it has

• an automatic recovery instance "initramfs" image that gets triggered if the router has crashed, and
• a normal firmware.

[hnyman]

@diagpope

tried to update one Belkin RT3200 and two Linksys E8450 that were already UBI converted via dangowrt (24.10.0) to 24.10.2 using sysupgrade.itb. They both refused the image as not compatible. The upgrade was only possible...
...
(4. restore backup)

Sounds like it is due to the missing/wrong compat_version option in /etc/config/system
You are overwriting the new value (set by the 24.10.0 image) with your restore of older settings.
You will likely run into the same problem with 24.10.3 etc. unless you fix it

Belkin RT3200/Linksys E8450 WiFi AX discussion

After the move to the new "fip in ubi" layout, I ran into bogus compatibility problem in the next sysupgrade: I noticed at the next sysupgrade a few days later that it complained about the sysupgrade image compatibility. I had to manually add the compat_version '2.0' option to /etc/config/system. The reason for the complaint is that although the first sysupgrade image uci-defaults had already set the compat_string, I had restored settings from backup after the fip/ubi change, and the restored …

[diagpope]

Thanks for this hint. I confirm that both routers had the compat string missing.
After I added it, they now accept the ubi*.itb sysupgrade.