Experiment...

I have a serious throughput issue. This is an idea for what it’s worth. You tell me. I am going to try to use 2 hpn cards , bridged , on an RB800 , both in station mode with same ssid. The thinking is if one radio is interfered with to the point of a few kilobits throughput , the other may not necessarily fall prey to whatever is causing the throughput degradation on the other card. The primary problem is that I have 3 ap’s , 6 -12 miles out , perhaps 60 degrees horizontal separation , that the throughput has become radically erratic. One minute it’s 30M , the next , maybe 1M , and all three are doing this. I scanned the horizon and there is nothing to speak of out there (Ubiquiti AirView). I’m grasping at straws here because I’ve got 80-90 clients out on these links and it’s dropping VPN’s , resetting web pages and in general reeking havoc.

Wait, you have 2 wlan cards in station mode on the same RB800 with the same ssid, connected to the same AP? Why?
They’re just self-interfering with each other. Disable one of them and then check the signal levels and ccq.
Use nstreme or nv2.

no , this is a thought experiment to address the problem of poor throughput. I currently am set up with what you suggest. It ain’t working My options are limited.