Dirty upgrade to 386.1-Alpha2 on RT-AC86U worked a treat - all scripts as per signature tested and happy - BUT broke my AiMesh to RT-AC5300 Node and nothing I could do to restore it [even pushed 386.1-Alpha2 to the AC5300 - reset factory - searched and failed many times]. Stock firmware for the AC5300 still on 384 - so didn't try that.
Reverted to RMerlin 384.19.0 on both routers [main and node] and back to rock steady throughout.
5300 will not work at all on this alpha for ai-mesh it seems. My main ac88 sees it, but will not detect it as a mesh node no matter what I do. That included full reset on both multiple times. manually setting it to a mesh node and a couple other combos. Hardwire and WPS connect didn't work. I can ping router but will not be detected as a mesh node. Despite me being able to ping it, when I try to access web gui or ssh, it will not load if in mesh node mode.
Going to go back to last 384.19 on 5300 to test and see if that will work with newest alpha2 on ac88 and report back.
UPDATE: Nothing I tried worked. It seems like this might be a specific issue to the 5300 because I was having all kinds of weird issues even setting it up in default mode.
I had to do a hard reset on all devices and go back to 384.19 to get everything working again. Will wait for next revision.
Thanks for all your hard work Merlin!