I was dumb into thinking ATH79 for this router (wndr4300v1) would be any good...
so I tried it...
upon first boot in, the router's WIFIs worked... funny 2.4G and 5G would be dropping wifis and just freezing the wifis
I was happy to see the whole flash amount was working
so after many tries and a lot of changing channels to make the wifis work... I got tired and I did a TFTP to go back to 19.07...
5g would NOT work at all... except only on the 149 channel apparently
went back to 18.06, the 5G worked quite a bit better, didn't test much, but at least the 5G worked with default settings, I did a sysupgrade to 19.07... and again the 5G worked somewhat in the beginning, but after a reboot with manually setting "option disabled =0" in etc/config... it's working only on channel 149...
so did the ATH79 build erased some part of the stock flash handling the 5G?
If you can collect logread output at the moment when you're seeing problems, that might help. 19.07.1 will be pushed soon as well (I think the buildbots are building it as we speak).
There's nothing dumb about trying ath79, but a lot of people adopt a 'wait and see' approach, so they only flash the stable images, while the release candidates are meant to be tested and iron out these kinds of kinks. 19.07 is the last release with ar71xx images, so it's important these kinds of issues can be fixed.