I'm looking too (Home set-up with OpenWrt and Ubiquiti - #6 by lpyparmentier), it's late I'll check everything being said in this topic later. For tl;dr: I've bad performance on 2 mesh Unifi LR-6 (~200mbp/s) on self installed+configured OpenWRT while I've very better (400mbp/s the limit of ISP) with Orbi RBK23 (original OS, apparently based on OpenWRT also). All running on 5ghz band.