WonderShaper limits the bandwidth too much

We use WonderShaper as a traffic control tool on our linux servers. We have 10Gbit uplink, and I want to limit the upload and download to be up to 1Gbit per server. My goal is to prevent a situation in which one server downloads a huge file and chokes the whole line.

All I need to do is to define what is my required upload and download bandwidth (kb) -

wondershaper -a enp0s3 -d 1024000 -u 1024000

However, whenever I'm testing iperf from a client to the same server I made the changes on - iperf3 -c {IPERF_SERVER} -t 60 I'm getting very low results, much less than the configured:

[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-100.00 sec  3.42 GBytes   294 Mbits/sec  2006             sender
[  4]   0.00-100.00 sec  3.41 GBytes   293 Mbits/sec                  receiver

Testing download (adding -R to iperf) leading to 950Mbit. Whenever I'm disabling WonderShaper, I'm getting almost 10Gbit for both upload and download.

Does anybody familiar with these issues using WonderShaper? Or is there anything in addition I can do in order to solve it?

That's the output of wondershaper -s -a enp0s3

qdisc htb 1: root refcnt 2 r2q 10 default 32 direct_packets_stat 0 direct_qlen 1000
 Sent 42101739 bytes 592924 pkt (dropped 0, overlimits 133 requeues 0)
 backlog 0b 0p requeues 0
qdisc sfq 30: parent 1:30 limit 127p quantum 6000b depth 127 divisor 1024 perturb 10sec
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
qdisc sfq 10: parent 1:10 limit 127p quantum 6000b depth 127 divisor 1024 perturb 10sec
 Sent 37916360 bytes 574353 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
qdisc sfq 20: parent 1:20 limit 127p quantum 6000b depth 127 divisor 1024 perturb 10sec
 Sent 4185379 bytes 18571 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
qdisc ingress ffff: parent ffff:fff1 ----------------
 Sent 3717886081 bytes 533558 pkt (dropped 639, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
class htb 1:1 root rate 1024Mbit ceil 1024Mbit burst 1408b cburst 1408b
 Sent 42102725 bytes 592931 pkt (dropped 0, overlimits 58 requeues 0)
 backlog 0b 0p requeues 0
 lended: 38 borrowed: 0 giants: 0
 tokens: 163 ctokens: 163

class htb 1:10 parent 1:1 leaf 10: prio rate 204800Kbit ceil 1003Mbit burst 1561b cburst 1379b
 Sent 37917346 bytes 574360 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 lended: 574360 borrowed: 0 giants: 0
 tokens: 852 ctokens: 163

class htb 1:20 parent 1:1 leaf 20: prio rate 409600Kbit ceil 972800Kbit burst 1536b cburst 1459b
 Sent 4185379 bytes 18571 pkt (dropped 0, overlimits 77 requeues 0)
 backlog 0b 0p requeues 0
 lended: 18360 borrowed: 38 giants: 0
 tokens: 225 ctokens: 94

class htb 1:30 parent 1:1 leaf 30: prio rate 204800Kbit ceil 921600Kbit burst 1561b cburst 1382b
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 lended: 0 borrowed: 0 giants: 0
 tokens: 968 ctokens: 203