Asus AC78U with '00:26:86:00:00:00 no address configured' issue -- help please

[Malibu]

Hi there. I'm on asuswrt-merlin 380.69_2, the router is stock. I'm having terrible problems with streaming messages "00:26:86:00:00:00 no address configured". I've read about the Quantenna compatibility issues and being affected by ios devices; I have put all ios devices onto the 2.4 Ghz network but something is still triggering this and it seems to overwhelm my router to the point that it is unstable and eventually reboots itself. It is very frustrating and I would just like my router to be stable. To confuse matters more, the thread at https://www.snbforums.com/threads/5ghz-goes-down.24165 indicates at the end that it should be fixed but it is clearly not on my router. Can anyone help me understand what I need to do to be stable? Thank you.