wr1043nd-v3 is "missing" from the list. The firmware for this model is available in ispyisail's firmware.
I think this option should be removed to stop people bricking their routers.
Since "Preserve settings" options could be faulty in more than 50% of firmware updates, wouldn't be better to remove that option
A better way would be to force everyone to manually (or automatically) download the settings backup, then restore it to the router after upgrade. This way, it will be possible to run some scripts to check if the backup files are valid or compatible with the latest firmware and make it possible to drop settings that will not work or brick the router. Before settings is restored, this also allows one to see the firmware upgrade works and the problem lies in the settings backup restore, meaning failsafe (or firstboot) will definitely fix it.
-----------There is something wrong with 1.9.1 when QoS is enabled. Without QoS, the router appears to function normally.
Symptoms on Archer C7
1) The router will be stuck in reboot loop
2) Unable to access router via web or SSH
3) Right after router boots up, when web interface is available. Clicking on Firewall will cause the web interface to freeze immediately, i.e. triggering (2) immediately
4) QoS does not recognize manually added L7 protocols, even though I have already updated L7index file and provided the pat file. (The same approach works on 1.8.1, so I am 100% sure I know what I am doing.)
5) After QoS is enabled, it may result in the router "freezing up", i.e. no internet or access to router. This is more apparent if you have a longer list of QoS rules than default.
I am able to reproduce the same problem on 1043nd v2. On the 1043nd v2, I used a freshly installed 1.9.1 Gargoyle firmware with no custom settings other than enabling Uploading QoS, adding new QoS classes and adding QoS rules. The router eventually get stuck in a reboot loop after save settings.
Note: WiFi was not enabled. Tests were done over ethernet.