Iperf3 with NAT doesn't send data after the connection is established

Hi Guys,

The problem is that Iperf3 with NAT doesn't send data after the connection is established, but if I use the fastpath of Netfilter, it will work normally.
For the NAT(iptables), I've tried two things, one is the MASQUERADE option, and the second is manually setting up SNAT and DNAT, but both results are not different.

OpenWRT v22.03-rc5, iptables v1.8.7 (nf_tables)
I shut down the firewall.

fw4 flush
/etc/init.d/firewall stop

Here is my environment

iptables -t nat -A POSTROUTING -d 192.168.1.111 -j MASQUERADE

image

iptables NAT settings
image

iptables

nft tables

Wireshark on Srv1

There is a Kernel option need to open?
Does anyone meet a problem like this?

Thanks!

Does the other peer receive all the packets correctly? Is it trying to send data over another port maybe?