I don't have a lot of time to investigate this further but I'm curious if it corresponds to any known issues....
I'm noticing that using an iPhone X and iPhone XS, my R720 performs fairly poorly in the down (AP -> Client) direction.
Setup: 80MHz channel 100 (it's clean, no neighbors), 5GHz-only network
On vSZ 5.1.1 MR1 Refresh: Downlink starts around 300mbps and quickly drops to 150-170mbps. Uplink stable at 550mbps.
On vSZ 3.6.2 MR2 + "b706" R730 AP patch: Downlink and uplink both stable at around 450-500mbps.
Interestingly, if I switch the client to a desktop with an Intel AX201 card, both vSZ environments perform the same. I also don't see the issue with a R730, it performs well against both clients with both vSZ versions.
Are there any known performance issues with iOS clients on vSZ 5.1.1?