The RT-AC86Us have been reliable for me and my customers since they were available. However, I don't think it is worth anything today (even a brand-new, in-box, example).
This router was the king of AC-class hardware. Until the entry-level RT-AX68U came along.
There are some odd regressions being discussed on the dnsmasq-discuss list from the PiHole guy (Dominik). https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2021q3/015598.html https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2021q3/015596.html I see Merlin is testing 2.86 out...
www.snbforums.com
Note that a single RT-AX68U was more performant, had more throughput, and lower latency than the pair of 2x RT-AC86Us it replaced. (Even if the customer insisted on a 2x RT-AX68U set up in the end).
Even for use as a mere Media Bridge today, AX class routers easily surpass it. Newer RF designs/implementations, newer SDKs, newer hardware. These all add up to making even the 'kings' of their domain seem
less after a few short years pass, in the tech space.
I wouldn't buy it.