The tcp_ndown test shows good latency and throughput, so that part of things is working well. The ax210 upload test is AWFUL, and looking more directly into that is needed. The rrul test is a reflection of that although the ath10k should be able to do about half in this case, and isn't because (IMHO) reads are starving writes on the current structure of the ath10k driver.
It's not "saturating the network" on the rrul test as completely overwhelming tcp's congestion control algorithms by having so much buffering in the ax210. It too, should have essentially less than 20ms,
and doesn't, and I have not poked into that driver at all. I did pick up an ax210 card since we've isolated that to be a problem in and of itself, regrettably I lack a laptop that has the m.2 slot in it to even try it. But I'll start poking through that driver to see what I can see in it.
It's kind of like the sith, when it comes to wifi. It's always two...