@Carl 

Hi Carl I seem to be having the exact same issue as American1776.

This is my hardware info:

Hardware: ArcherC9 v1

Firmware:3.17.1 Build 20180125 Rel.56387n

I can't seem to get any throughput beyond 20mbps on any wifi device. Wired still appears to be working, but I don't have any wired devices and my entire wifi setup at home is painfully slow.

Is there anything else I can do?

@Carl

Thanks for your help. Before my initial post I attempted what you suggested previously, so I have already disabled NAT boost and changed the bandwidth control settings and I had no result. I just cycled through all possible channels and the result is the same. I'm still not getting more than 20mbps throughput on any wifi device on any channel or band (2.4 ghz and 5 ghz). Could this be an end of life issue as well like American1776?

Thanks again.

@Carl 

Ok I'll monitor the traffic but I can already tell you that I only really have one device that utilizes most of the network capacity at any given moment. I don't think this is due to a network utilization issue because the throughput problem has just started to manifest in the past few days and everything was fine before that. I haven't changed my network usage patterns since then. If this turns out to be a non-issue what else can I do?

Thanks!

@Carl 

You're absolutely right, it's never good to jump to conclusions. That being said, it's been roughly a day since I began monitoring network usage. It looks like what I expected to see. There don't appear to be any devices using more bandwidth than usual. Is there anything else I should look into?

Thanks!