Hello.
Mikrotik CCR1036, fw 6.46.7. Approximately 400 PPPoE subscribers. Problem with speed limit for one subscriber of 400 Mbps and above. The incoming speed is accelerated to 700 Mbps, and the outgoing speed is limited to 300 and no more. I tried to change the queue type small to 50, 100, 1000 packets, sfq, 1 packet queue, pcq, disabled MRRU - it doesn’t help. Changed the limit in the queue from the interface to the ip address - did not help. If you remove the queue, then the outgoing speed accelerates to 400, no more. There is no such problem with DHCP cleints. With a cisco, there is no such problem, but there is no way to change the mikrotik to a cisco. I also tried it on firmware 6.48.6 and on CCR1072. The cpu max load is about 30-40%. What do you advise?
i think ccr1072 at such a high average cpu usage can have some cores exhausted
on winbox
check system - resources - cpu and click on load header to see it sorted by usage to see how much cpu usage you have ond your most tasked cores, specially when you do bandwidth limit tests on pppoe
check profile to see more specific info about cpu cores usage, here you need to click on usage header to see it sorted by load
as a sugestion, for BRAS Role and specially PPPoE i prefer to use 2 x ccr1036 and split the load between them than a single ccr1072, you get better performance and capacity and is cheaper 
i think is better to let ccr1072 only for core or border router in fast-track or fast-path mode
Hi guy old topic..
but we have same sort of issue..or at least similar our issue is on WIFI.. on cable pppoe goes easy 800 to 900mbps fia fiber GPON olt connected on 10G uplink direct to sfp+2 on ccr1036 where pppoe-server is setup..
but problem is on wifi6 ax.. and wifi5ghz.. cannot go over 400mbps max.. average speeds on 3xx mbps download and upload goes nearly 700mbps.. we are doing tests internally insider our network on different test servers.. nperf, speedtest ookla internal we have on our isp.. and fast server.. same thing cable goes easy 900mbps on same wifi6 router.. but on wifi6 ax devices cannot go over 3xx mbps.. any ideas of what this could be?