This has been driving me nuts - hoping someone can figure this one out.
My setup is pretty simple:
2 Archer C7's. One is the primary (WAN, DNS, Router, DHCP). One is a secondary access point (uses primary IP for DNS/Gateway, DHCP disabled). Nothing else too fancy.
When i enable SQM in the simplest config (cake/piece-of-cake) on my primary (with 50000kbps down, 5000 up in settings), the WAN bandwidth available to my 2nd router is capped at under 5Mb/s. I have 50+ available. Traffic levels don't matter. Disable SQM,and it returns instantly.
You need to explain better how your both C7s are connected (what's the WAN port of the AP-C7, and to which port of your Router-C7 is it connected?) and how your SQM is configured.
Did you configure SQM for your LAN port instead of your WAN port? There's a couple of things that I cannot explain with that kind of misconfiguration, so that might not be your only problem. But just in case: If you did apply SQM to your LAN port instead of your WAN port, switch that and make SQM deal with WAN only.
Well, in that case the result is predictable, albeit surprising. In that situation the meaning of ingress and egress flips in regard to internet download and internet upload (and I realize you realized that already, but for others stumbling over this thread let's be explicit). The reason is that ingress and egress always refer to the router and internet packets coming from the internet will be send via the LAN interfaces egress direction and hence were shaped to <= 5Mbps. Since the directionality of shaper's is a bit confusing the GUI attempts to make the "normal" situation SQM instantiated on the WAN interface novice friendly, at the cost of making other configs slightly more opaque. But the alternative would be to be confusing to all users and sqm squarely aims at novice users (the shaper for the rest of us ;))
When playing with SQM, it wasn't 100% clear to me as well. I'd expected to be correct what appeared to be actually correct. But since I had some doubts, I changed WAN and LAN, applied SQM to "br-lan" and "eth0.1" and flipped the actual values of ingress and egress in order to find out what happened when.
But the thing I was talking about when I mentioned "There's a couple of things I cannot explain" basically is: If you really only mixed up in and out (no matter if its switching ports or ingress/egress values), then you should have noticed the limit to 5MB download speed not only on your AP-C7 but on every connected client.
Or is the only client you have connected to that AP, hence you don't have another computer that is not connected to the AP which could have noticed that limit=
When playing with SQM, it wasn't 100% clear to me as well. I'd expected to be correct what appeared to be actually correct. But since I had some doubts, I changed WAN and LAN, applied SQM to "br-lan" and "eth0.1" and flipped the actual values of ingress and egress in order to find out what happened when.