Donwlink modulation jumping results in slow speeds

Have a subscriber who is complaining of slow speeds.

Uplink modulation is rock solid.

Downling modulation is good UNTIL the connection is stressed with high data flow. The Downlink modulation then drops and jumps around which is most likely the cause of his issues.

This is a problem I’ve noticed throughout different networks we have.

How can I get the Downlink modulations to be as solid as the Uplink modulation? If it were interference why is the Uplink stable?

Screen shots from the SM in question

AP firmware e2.3
SM 8.1.4

What is the LOS and link distance of this sub, and how is your AP configured? We’ve seen poor results once trees show up, the 24.41 dBm TX power doesn’t look so nice to me.

Also we’ve seen VERY unpredictable behaviour from interference on these things. Doesn’t seem like the Moto sector antennas have any front-to-back separation whatsoever. Don’t be so sure that interference isn’t the problem

I’m with salad on the possible interfenrce,

how far apart are your sector antennas? what kind of down tilt do you have?

also, whats your harq retry count? set it to 5 to help out, its not a fix but a bandaid to tie over your sub until you get the root problem fixed.