netem ratelimit stops limiting rate after short time and restores to default

I have experienced a couple of times that netem stops working when I apply qdisc. This happened with both rate limit as well as loss.

For example, consider a scenario: Internet <------>(eth1) A (eth2)<------> (eth3)B

PC A is connected to an internet access point via ethernet port eth1. PC B is connected to PC A via port eth2 of PC A. So, basically, PC A is a bridge that I configure using OvS. I apply netem rule on eth2 and expect it to be reflected on PC B.

Now, in PC A, I applied a rate limit on eth2 of 30Mbps with a limit of 1000 using the command:

tc qdisc add dev eth2 root handle 1:0 netem rate 30000kbit limit 1000

Then I ran the iperf3 server on PC B and test the bandwidth by running the iperf3 client on a different PC (say 'C' that is connected to the network). The iperf3 result is:

[ 4] local xx.xx.xx.xx port 54838 connected to yy.yy.yy.yy port 5009
[ ID] Interval Transfer Bandwidth Retr Cwnd
[ 4] 0.00-1.00 sec 3.92 MBytes 32.8 Mbits/sec 0 185 KBytes
[ 4] 1.00-2.00 sec 3.50 MBytes 29.4 Mbits/sec 0 210 KBytes
[ 4] 2.00-3.00 sec 3.50 MBytes 29.4 Mbits/sec 0 210 KBytes
[ 4] 3.00-4.00 sec 3.38 MBytes 28.3 Mbits/sec 0 210 KBytes
[ 4] 4.00-5.00 sec 3.50 MBytes 29.4 Mbits/sec 0 210 KBytes
[ 4] 5.00-6.00 sec 3.38 MBytes 28.3 Mbits/sec 0 210 KBytes
[ 4] 6.00-7.00 sec 3.50 MBytes 29.4 Mbits/sec 0 210 KBytes
[ 4] 7.00-8.00 sec 3.50 MBytes 29.4 Mbits/sec 0 210 KBytes
[ 4] 8.00-9.00 sec 65.6 MBytes 550 Mbits/sec 142 210 KBytes
[ 4] 9.00-10.00 sec 109 MBytes 918 Mbits/sec 0 210 KBytes

[ ID] Interval Transfer Bandwidth Retr
[ 4] 0.00-10.00 sec 203 MBytes 170 Mbits/sec 142 sender
[ 4] 0.00-10.00 sec 203 MBytes 170 Mbits/sec receiver

Initially, I am getting around 30Mbps but in the last two runs, the throughput is much higher than 30Mbps. I tried iperf3 again multiple times. Then it was fine. Why netem has this inconsistent behavior?

Another example where I cap rate to 50Mbps, the first iperf3 gave correct rate-limiting but one the second iperf3 attempt I got the inconsistent rate-limiting (as shown below):

[ ID] Interval Transfer Bandwidth Retr Cwnd
[ 4] 0.00-1.00 sec 6.05 MBytes 50.8 Mbits/sec 0 210 KBytes
[ 4] 1.00-2.00 sec 5.75 MBytes 48.2 Mbits/sec 0 210 KBytes
[ 4] 2.00-3.00 sec 5.75 MBytes 48.2 Mbits/sec 0 210 KBytes
[ 4] 3.00-4.00 sec 5.75 MBytes 48.2 Mbits/sec 0 210 KBytes
[ 4] 4.00-5.00 sec 29.8 MBytes 250 Mbits/sec 143 210 KBytes
[ 4] 5.00-6.00 sec 110 MBytes 920 Mbits/sec 0 210 KBytes
[ 4] 6.00-7.00 sec 109 MBytes 914 Mbits/sec 0 210 KBytes
[ 4] 7.00-8.00 sec 109 MBytes 915 Mbits/sec 0 210 KBytes
[ 4] 8.00-9.00 sec 109 MBytes 914 Mbits/sec 0 210 KBytes
[ 4] 9.00-10.00 sec 109 MBytes 914 Mbits/sec 0 210 KBytes

[ ID] Interval Transfer Bandwidth Retr
[ 4] 0.00-10.00 sec 599 MBytes 502 Mbits/sec 143 sender
[ 4] 0.00-10.00 sec 598 MBytes 502 Mbits/sec receiver

After the fourth run, it appears that netem ratelimit is simply gone and the network is back to its default rate.

I have seen this behaviour when I introduce loss using netem. Please, any help to fix this or explain this inconsistent netem behaviour would be helpful. Thanks.