TCP - Iperf Test only transmit small amount?

Hi, I do have 2 iperf server deployed in two sites, not when Iperf A is the client I can able to transmit up 16m(bandwidth) only while if the client is Iperf B it can transmit more than 16m (up to 100m which is our target amount)

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Topology:

IperfA ----R1--R2---R3----IperfB

test 100m bandwidth link

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IperfA to IperfB

IPERFB: iperf3 -s -p 5210 -B iperfb -i 2

IPERFA: iperf3 -c iperfb -p 5210 -i 2 -t 200 -w 1650k –P 2

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IPERFB:iperf -s -p 5209 -B iperfb -i 2 -w 1650k

IPERFA:iperf -c iperfb -p 5209 -i 2 -t 500 -w 1650k –P 2

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tried using different version but still got the same result, IperfA(client) send only up to 16m also seen on interface of R1

facing iperfa and verified that the received amount from IperfA is just 16m.

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Note: when we test the opposite direction B->A, B can transmit up to 100m.

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Thanks